Hi Jesse,
If none of the other users are affected, I suggest to follow these steps:
1. Save a PLN from the current status of your project, to have a backup from your data.
2. Go to Teamwork > Projects > Reload project from Server option > in this case ARCHICAD deletes the current local cache and replaces it with the actual status of the project on the BIMcloud
3. Copy data back - try to Send & Receive
4. If you can successfully Send & Receive, then probably ARCHICAD wanted to send something up again to the server by your name, which was already there
5. If not, then there might be a corrupted element in your modification
6. In this case, run an Open & Repair on your PLN file, and repeat steps from 2 to 4
7. If you still have no luck, you can try to re-share the project
8. Worst case scenario is that you contact your local support
Kind regards,
Noémi Balogh
Community Expert, Admin