So this is existent everywhere, all servers and scenarios I've been on. At least ones where wall damage can be turned on and off, it might relate to that I'm unsure.

So basically if say a fence is destroyed totally, so only posts are left, or same with a side of a watchtower. If you re build the frame, it'll have a red dot as if it is ruined, or sometimes badly damaged orange. I am unsure if this impacts its hp, but obviously despite being red/ruined it physically exists.

Then in a similar idea. If a wall or frame is say damaged, you can repair it forever with it making no progress, you could use 20 planks and a stack of 99 nails on it, the damage symbol won't change and it will just let you keep trying to repair it forever, using up all your nails and planks for no visual gain.

The repairs and rebuilding happen with base damage off, so I'm not sure if that's relevant. The only "fix" is to totally dig up the posts and remake the wall. Obviously that's not viable on a watchtower.