I've just broken a 2 by 2 colossal chest, and when I places the Core again to create a new one, a 2 by 2 chest became visible without me having placed those blocks!

I can also access it and use it like a working colossal chest. Relogging doesn't fix it.

Error visible in chat:
[23:56:31] [Client thread/INFO]: [CHAT] [ColossalChests]: Found dimensions 0x0x0, while a minimum of 1x1x1 was expected.

This only happens when you break the core first before the rest of the multiblock structure.