Web interface vs Storage mismatch

I’m running Urbackup 2.4.13 on Ubuntu 18.04.5 LTS with a LaCie 30TB Storage Array.
At the end of October there was a steep drop in the Storage Usage graph from 3.4TB to 900GB, which, as far as I can tell, was not of my doing.
The number of backups available showing under each client also reduced to between 0 and 20 (seemingly random), but the number bears no resembalance to the actual number on the storage array.
I’m not sure exactly what went wrong, but is there a way to refresh the database to bring back the missing backups, from the web interface’s point-of-view?