Firewall remains pending

Since a few days one of our firewalls is refusing to sync properly

I have already tried to remove the firewall from the group and adding it back, but syncing will keep as PENDING at 0%. I have also tried to switch primary and auxiliary but so far all to no avail.

Firewall is currently at firmware SFOS 19.0.1 MR-1-Build365 and has until recently always synced.

What can I do to get it to sync again?

Mistakenly added the picture twice.
[edited by: apijnappels at 2:07 PM (GMT -8) on 3 Feb 2023]