I have exactly the same problem on one of my Mun bases. Multiple other building sites all over the Kerbol system are just fine. Big fan of your work.
The survey station on the bugged base is manned by a level 3 pilot and the stakes are definitely less than 50m away from the center of mass of the base. However, I have a hypothesis, how it can still be distance related to stakes..
In my case, the problem developed immediately after launching a relatively big build, boosted by 2 SRBs. When I later switched back to the base, two things had happened:
1. One of the survey stakes (X-) was gone. Possibly, the SRB exhaust blew it off, and landed it either so far away that I could not find it easily, or possibly below-ground.
2. The survey station Show UI window was bugged out, exactly like on the screenshot posted by Barcel.
I have been able to *temporarily* remedy this problem by removing existing stakes and re-planting them. But the problem re-occurs shortly after that, tho none of the stakes have been blown away subsequently.
Could it be that the survey station picks up two X- stakes and gets confused? Or maybe the missing X- stake ended up still within range, but in a glitched out place?
I will experiment some more, later today.
After experimentation:
Got rid of that glitch with survey station UI being messed up.
It was indeed a rogue survey stake. Once I switched on "Toggle Unknown" in the KSC tracking station, I could see it floating approximately 10km above my base, whilst mouse-hover over it showed it as "landed".
Once I terminated that object in the tracking station, the base went back to normal.
