***SOLVED***
This is the same post i posted on the Reddit forum, but it is quite inactive, so I paste it here
I've been using flightgear since 2017 but I quit it about a couple years ago. I downloaded it yesterday and made a few flights. Everything good. But I remember that there was buildings and stuff on the airports. For example, in LEBZ, there was a gate with "Talavera La Real" big sign. As well as in LEMD, there was this colorful gates. At this moment, my scenary is completely flat. I see runways, taxiways, and lights and stuff, but no buildings.
Any help? Thanks!!!
*** The fix to the problem is adjusting your "level of detail ranges", and having the "high" ones at least 1 km away. That will make buildings appear, but also lower your framerate.
Hope this helps