I'm playing Staxel CE multiplayer. We were changing the way our tree farm area looks and there was a 4x4 area we couldn't place any blocks in. We decide to reload the game and one of the trees that we had already broken was there again but not actually. When breaking it a second and third time, it disappeared without dropping any wood and the 4x4 area is still unusable.
If it helps, before this happened, we had untilled some of the tilled dirt before removing this tree and haven't done that for the other trees, which were chopped down without any issues.

[Edit]
Somehow, thankfully, it fixed itself but I'm going to leave this up because it was still an issue we had.