I've reviewed the information in GUI Login Loop already. The root filesystem is currently 18% full. I've tried clearing browser cache, reloading the GUI and private mode.
I'm kind of at a loss because Chrome allows login without issue.
The system is OMV on top of a Raspberry Pi 4. It was happening before and I've rebuilt the system from the ground. I was able to login without issue yesterday after initially building the system. Today - nothing.
**Edited to add...** I have another OMV 5 server running. That one exhibits none of this behavior. I'm able to login properly 100% of the time from Firefox.
After further testing... I was accessing my other OMV server behind NginxProxyManager using it's domain. If I try to access that via IP - same behavior.
So two OMV servers I cannot login via Firefox.