We had this problem. Was even worse since half the staff attempted to investigate and got caught in a kick cycle, we had to use bloody CMD block clocks to tp them out. Believe me, I share your frustration.
The only way around it we found immediately, was to use our World Edit plugin. We managed to get a radius around our spawn, which was the affected few chunks, and use //expand vert to get every block in those chunks and turn signs to bedrock.
If on the happy coincidence you have W.E., then it'll help solve the problem short term, and then long term would be the upgrade as these guys are saying.
And no it's not funny. For god knows how many hours, the server was inaccessible and it took half the staff to resolve the damn problem. It's people like you RoboBear and ThriveCraftMC that ruin Minecraft for other people.
