[2020] Blimps can't place blimp stops

Definitely check to make sure you don't have a filter enabled on the menu. I've done that more than a few times and wondered where something went.

It could be Steam's connection that's struggling for you. At least that's also what happens when Steam isn't connecting right. Sometimes I can't get it to update mods/assets even though I restart the game several times and it should update automatically. For me logging out of Steam and restarting Steam does the trick and makes it reconnect properly.