High resolution heightmaps not working anymore

Version: 1.0.72.0

Frequency: Consistently

Severity: Blocker

Context:
Aerosoft Antarctica Casey YWKS
Aerosoft Antarctica Rothera EGAR (AQ80 remote skiway)

Bug description:
About 1-2 years ago in MSFS2020 the restriction has been lifted that heightmaps are limited to the same resolution as the underlying terrain. This was a huge improvement above the previous condition as it allowed huge terrain improvements in remote locations without any good DEM available.
Now we seem to be back to square one. The screenshots show two locations where this is very obvious. It is not as bad in other regions but certainly messes up all adjustments there objects have been placed at an elevation value in regards to the underlying terrain.

Repro steps:
Load Casey helipad in above mentioned package.

Attachments:

Near Casey helipad in MSFS2024 (ignore the issue with the snow for now, this has been reported elsewhere). You can see the animated vehicle following the heightmap but the heightmap is not being displayed:

Same location in MSFS2020:

AQ80 skiway (in Rothera EGAR package mentioned above) in MSFS2024. Wreck shown is at a fixed elevation, heightmap underneath obviously not shown at all or not at full resolution:

Same location in MSFS2020:

As a small side-reference: Sunken default model chairs at VNPL in MSFS2024, which have not been placed at a fixed elevation but at a relative elevation towards underlying terrain/heightmap. Makes it obvious that the heightmap is not loaded at the same resolution as previously in MSFS2020:

Hmm… to put some more context to it:
Ignore my latest comment about the chairs, they just don’t have the legs, which is an LOD, not an elevation related issue as mentioned here:

After some further observation I believe that heightmaps ARE either being loaded as before or not at all. What however I do not understand yet why some are loaded, others are not:

Aerosoft EGAR Rothera with heightmap loaded and terrain bugfixing. Looks good:

Aerosoft YWKS Casey helipad area with terrain bugfixing active but heightmap not rendered: