Issue Roundcube does not show used storage space

[cool_sh]

Server operating system version

AlmaLinux 8.8

Plesk version and microupdate number

Version 18.0.56 Update #4

I have a couple of mailboxes where the used storage inside Roundcube is not displayed, only "unknown".

It seems it is a problem with huge mailboxes where more than 1 GB is used. On same domain another mailbox with only 40 MB it is fine.

How to solve that?