Subscription downgrade not syncing, but real values correct

CentOS 7.2 64 bit, 12.5.30, latest version

Active subscription: 500 MB mailbox size, but no mailboxes, only redirects.
New subsription: 10 MB mailbox size.

Changing subscription to new subscription fails:
subscription value: 500 MB
package value: 10 MB
available value: 500 MB
Wrong, because there are not mailboxes, meaning it is impossible that a mailbox is set to 500 MB.

Tried to run
/usr/local/psa/admin/sbin/statistics --calculate-one --domain-name=DOMAIN.TLD
to recalculate statistics...

Subscription downgrade not syncing, but real values correct