I have some theories for what is wrong but here is what I need to verify/test/get more infor

Can I get a link to the SOP you used/followed to restore UPS?

Did you just take a backup from one cluster and deploy it to a different cluster?

If so did the addressspace/address/messaginguser CRs get migrated? Those have cluster specific metadata in them provided by enmasse and should be recreated by the UPS operator, not copied from one cluster to another.