Thank you for sharing your "scenery_packs.ini" content, Nick. This definitely helps in pinpointing the issue and providing a more tailored solution.
From what you've provided, it seems that the order of your scenery packs could be causing the problem with missing airport buildings. The "scenery_packs.ini" file works in a top-down approach, with the sceneries at the top overriding those below. Hence, the priority should be given to the most localized scenery (e.g., airports) followed by regional sceneries and larger area photoreal sceneries, with libraries and global airports towards the bottom.
Here's how you can rearrange your "scenery_packs.ini" to potentially resolve the issue:
000 Version
SCENERY
// Airports should come first in specificity
SCENERY_PACK Custom Scenery/X-Plane Airports - KBTV Burlington/
SCENERY_PACK Custom Scenery/Aerosoft - LFMN Nice Cote d Azur X/
SCENERY_PACK Custom Scenery/Aerosoft - LPFR Faro/
// ...add the rest of your specific airport sceneries here
// Next, include city-specific landmarks
SCENERY_PACK Custom Scenery/X-Plane Landmarks - London/
SCENERY_PACK Custom Scenery/X-Plane Landmarks - Berlin and Frankfurt/
// ...add the rest of your landmark sceneries here
// Then, regional sceneries and VFR specifics
SCENERY_PACK Custom Scenery/simHeaven_X-World_Europe-1-vfr/
SCENERY_PACK Custom Scenery/simHeaven_X-World_Europe-2-regions/
// ...continue with simHeaven packs
// Overlays and meshes come after specific and regional sceneries
SCENERY_PACK Custom Scenery/yOrtho4XP_Overlays/
SCENERY_PACK Custom Scenery/yOrtho4XP_Overlays_v3/
// Libraries should be next
SCENERY_PACK Custom Scenery/simHeaven_X-World_Vegetation_Library/
SCENERY_PACK Custom Scenery/Orbx_XP12_Library/
// Global airports come towards the end
SCENERY_PACK GLOBAL_AIRPORTS
// Photoreal sceneries should be one of the last entries
// Add your photoreal sceneries here, like Florida and California
// Meshes should be at the very bottom
SCENERY_PACK Custom Scenery/Orbx_B_EGLC_LondonCity_Mesh/
// Add any other mesh packs you may have here
Please reorganize your "scenery_packs.ini" accordingly and ensure that you have all your specific scenery packs listed in descending order of priority. Once this is done, restart X-Plane 12 for the changes to take effect.
If you still experience issues with missing buildings, it's worth checking if there are updates available for your sceneries or if there are known issues with the versions you're using.
Let me know if this reordering solves the problem, or if you need any further assistance. Happy flying!