I can confirm the problem.
Also I thought I was going crazy… few days ago I had a flight around the area of LSZX Schanis Airfield where the mountains are really great in the new terrain photogrammetry but yesterday I just noticed no houses are generated anymore.
Although in this picture the image is not that good (is a screen capture from an area I was flying where the houses are visible and existing few days ago. The city in here is Niederurner close to the Walensee lake close (a bit South) of lake Constance OP reported.
Now you can clearly see even in pre flight map that only the trees are loading and cast shadows and houses are just the pictures from satellite. Same city for example but the area is large as previous posters reported.
This bug is possible to be linked with the resolution of this bug here?
Meaning users reported the autogen buildings where conflicting with photogrammetry ones and maybe the solution for this previous bug created this new one?
I (personally) tried to clear caches in MSFS user folder ( here: C:\Users\USER\AppData\Roaming\Microsoft Flight Simulator 2024\cache ) and in Steam folder (I have Steam variant) from here in my case: ( D:\SteamLibrary\steamapps\common\Limitless\cache) , I cleared scenes indexes (from here: C:\Users\USER\AppData\Roaming\Microsoft Flight Simulator 2024\SceneryIndexes), cleared rolling cache file. I tried to uninstall and stream the World and City updates for Germany and Switzerland with no success of stopping the bug.
Like others said turning off Photogrammetry makes houses reappear. Of course this solution is not at all ideal.