Log into your Impero Server>Help>Display Statistics.

Click on Debugging.

Tick - Enable debugging menu on client right-click menu.

Still in Impero Server>Connection and select all the devices (this can easily be done by clicking the grey arrow next to Computer name).
Right-click anywhere>Debugging>Resync and sync everything. After that, verify if in Sync.

This should clear the issue. Make sure you untick Enable debugging menu as enabled on the third step.

Addition Notes
- If the above does not fix the issue please check that the server and the client version are the same.