We have a Connection – "Glaciers - WHS currently (or at the date of inscription) containing Glaciers" which lists 37 WHS.
A report has just been published titled "Disappearing WH Glaciers as a keystone of nature conservation in a changing climate" which identifies 46 WHS containing glaciers and identifies 21 of them which could lose all glaciation by 2100 in a "high emission scenario".

I have tried to identify the differences between our list and that of the report

Here is a summary of the report on IUCN's Web site –
https://www.iucn.org/news/world-heritage/201904/almost-half-world-heritage-sites-could-lose-their-glaciers-2100

Here is the full report –
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018EF001139

And here is a comparison of the 2 lists
We agree on the following 34
Canadian Rocky Mountain Parks
Dolomites
Durmitor
Glacier parks
Golden Mountains of Altai
Great Himalayan National Park
Heard and McDonald Islands
Huascaran National Park
Ilulissat Icefjord
Khangchendzonga National Park
Kilimanjaro National Park
Laponian Area
Lorentz National Park
Los Alerces National Park
Los Glaciares
Mount Kenya
Nanda Devi and Valley of Flowers
Olympic National Park
Pyrénées - Mont Perdu
Qinghai Hoh Xil
Rwenzori Mountains
Sagarmatha National Park
Sangay National Park
Swiss Alps Jungfrau-Aletsch
Swiss Tectonic Arena Sardona
Tajik National Park
Te Wahipounamu
Three parallel rivers of Yunnan
Uvs Nuur Basin
Volcanoes of Kamchatka
Waterton Glacier International Peace Park
West Norwegian Fjords
Western Caucasus
Xinjiang Tianshan

They have the following 12 which we do not
Historic Sanctuary of Machu Picchu
Huanlong Scenic and Historinc Interest Area
Nahanni National Park
Natural System Of Wrangel Island Reserve
Putorana Plateau
Sichuan Giant Panda Sanctuary Wolong Mt Siguniang and Jiajin Mountains
Tongariro National Park
Virgin Komi Forests
Virunga National Park
Western Tien-Shan
Yellowstone National Park
Yosemite National Park

And we have the following 3 which they do not
Aasivissuit - Nipisat
Hallstatt-Dachstein
Madriu-Perafita-Claror Valley

So – why the differences??
We have –they don't
Aasivissuit – Nipisat - only inscribed in 2018 so probably not included in the study
Hallstatt-Dachstein - We note "Hallstatter Glacier and Schladminger glacier". I note that the study ONLY included "Natural WHS". It counted "Mixed Sites" but doesn't seem to include Cultural Landscapes (CL) which have no natural values (even though it does include Natural/Mixed sites whose Natural values do NOT include contemporary glaciation - such sites are however identified as such) and this is probably the reason for its exclusion?
Madriu-Perafita-Claror Valley – We note "Contains "rocky glaciers"" but with no reference/link. Assuming that "Rocky Glaciers" do exist the CL reason, as above, probably explains the exclusion by the study.

They Have – we don't
All should be considered for addition to our connection?? Though it would seem worth identifying the glaciers involved and why we "missed" them!
Machu Picchu - Salkantay Mountain and Glacier is within the WHS Southern boundaries - https://en.wikipedia.org/wiki/Salcantay
Huanlong - "Xuebaoding, or Snow Mountain Peak, is permanently snow-covered and features the easternmost glacier in China" (IUCN eval)
Nahanni - This is a difficult one to assess! It was inscribed way back in 1978 and has no Nomination File available, The IUCN assessment is very thin and the map is rather poor!. BUT the AB eval does say "it would be desirable to incorporate the entire upstream watershed in the World Heritage Site even if it is not included in the National Park." in 2009 the NP was expanded massively and, inter alia, now includes the "Ragged Ranges" . This report ( http://www.ccrnetwork.ca/documents/Publications/Demuth%20et%20al%202014.pdf ) states " NNPR now includes, amongst other lands, a significant portion of the headwaters of the South Nahanni River and its glaciers (Fig. 16.1). Prior to the expansion, only a very small portion of glacier cover within the Ragged Range was encompassed by the Park.". BUT - the extension has NEVER been added to the WHS by Canada - The UNESCO entry states "In 2009, Canada greatly expanded the limits of the national park by adding 2,500,000 hectares to establish the Nahanni National Park Reserve. The expanded protected area now totals about 3 million hectares and provides important protection to the property's geological heritage and the South Nahanni River system. The boundary of the World Heritage site remains as originally inscribed. Over 95% of the World Heritage property is now surrounded by the larger national park reserve boundary,". So we have a significant amount of glaciation in the "Ragged Ranges" which are part of the NP but NOT a part of the WHS - and a comment "Prior to the expansion, only a very small portion of glacier cover within the Ragged Range was encompassed by the Park". The Table provided by the Study identifies a "Mean volume" of glaciers in the WHS as being only 0.0077 Kms sq!! On that basis it would seem that the original WHS DOES include a very small amount of unidentified Glaciation - even though the majority of Glaciers in the NP are outside the WHS.
Wrangel Island - Britannica says there are "No Glaciers" https://www.britannica.com/place/Wrangel-Island but the Study table identifies a "Mean 2017 Volume" of 0.028 Kms Sq. Needs more investigation? ( it couldn't be could it that the Study has been trying to increase the number of sites which are going to lose Glaciation by including some very marginal ones ???!!!)
Putorana Plateau - Nom File states "The modern glaciation of the Putorana, despite of good precondition for its development, is insignificant. In the northeastern and northern part of the mountains there have been noted only 22 small glaciers with the total area of only 2,5 sq.km."
Sichuan Panda Reserve - "the land is heavily ridged, forested and deeply dissected by the valleys and gorges of perennial rivers falling from the glaciated snow-covered peaks" (AB Eval) - Mt Siguniang https://en.wikipedia.org/wiki/Mount_Siguniang
Tongariro - Wiki states "Small glaciers are present on the summit of Mt. Ruapehu today.....Glaciers were last present on Tongariro during the Last Glacial Maximum"
Virgin Komi - The study identified a mere .0850 Kms Sq of current "mean volume" of Glaciers! I have (so far) been unable to identify any independent confirmation of this
Virunga - shares glaciated peaks with Rwenzori.
W Tien Shan - A number of the inscribed elements include contemporary glaciers e.g Aksu Jabagly - "The largest glaciers are situated in the basins of rivers: Zhabaglysu – Jabagly glacier (2.63 km2), Baldybrek – Shunkulduk glacier (2.56 km2), Aksu-Amansai glacier (1.02 km2). The area of most glaciers does not exceed 1 km2 " (Nom File)
Yellowstone - I still can't find an extant glacier inside this WHS -and the study's main "table" doesn't identify any "Glacier volume" even though it includes Yellowstone in its list! The NP Service's Web site doesn't mention any contemporary glaciers is its section on Glaciation ( https://www.nps.gov/yell/learn/nature/glaciers.htm ). There are Glaciers in the nearby Tetons - but outside the WHS. Inclusion on this connection not currently justified unless we simply use its inclusion in the Study as justification!
Yosemite - Lyell and Maclure glaciers
https://www.nps.gov/yose/learn/nature/glaciers.htm

Thanks a lot for the legwork, Solivagant!
I'll keep the 3 we have extra and will add the 'new' ones where they could be identified

I'd settle for a 'No' for this one. The nom file says: " It is critical that the Islands were not covered by glaciers in the Pleistocene, although a few traces of mountain valley glaciation only are found in the central part of Wrangel Island. "
-> seems a bit similar to Yellowstone, as traces and effects on the landscape may be found, but there are currently no glaciers