Years ago there was even an official Teamwork guideline by GS to leave the project every week or two.
Save the project locally and load it back up on the server, then the team joins again.
In an office where I worked some time ago I now dimly remember we had a similar problem, but with walls or so.
Doing the steps above helped back then and saved us from going crazy.
Just shooting my shot, you know.
Only GS can now help.