This is caused by line 181 in /usr/sbin/omv-cups-avahi. The usbdevs.get for this printer model returns a property containing a colon (in this case the value is "CLS:PRINSTATUS:BUSY"). The kv.split(':') cannot handle the string containing two colons. Changing to kv.split(':', 1) resolved this issue.
This is caused by line 181 in /usr/sbin/omv-cups-avahi. The usbdevs.get for this printer model returns a property containing a colon (in this case the value is "CLS:PRINSTATUS:BUSY"). The kv.split(':') cannot handle the string containing two colons. Changing to kv.split(':', 1) resolved this issue.
Another user reported this issue here: https://forum.openmediavault.org/index.php/Thread/11678-CUPS-with-ML-1640/