UPDATE:
I was able to get the backup jobs running on the (now remote) target storage. The issue had to do with network path changes. Ideally the software would communicate better about such things. In fact, the logs show CBB could tell the target folder was probably a CBB backup, so it skipped it.
Once the backup paths were resolved, the jobs seem to run again, however, it's clearly backing up files that were already backed up - thus losing the benefit of the seed backup.
MSP360 won't support my legacy paid software without me first buying the new licensing model and software, yet I don't even know if there's an upgrade path. Paying is not an issue - but throwing money at something that breaks the backup makes me cautious. It appears their focus has shifted to cloud vs. self-hosted / remote repositories.

I should have mentioned I'm using remote access to make changes (Teamviewer).
'All the work' meaning renaming / applying permission?

All great and expected questions.
Yes, this is a remote share on a PC. Both premises are via 100/100Mbps fiber internet.
I did add permissions to the share and can access it remotely.
HOWEVER, I did just find that the share name itself was not what is was before, so I've renamed it - applied permissions, and am crossing my fingers.
Logs don't indicate anything 'not' happening - so I'll let this one spin for a while.
Backup Storage tab shows spinning icon and 'retrieving data' - but no other updating indications of what's happening 'under the hood'.
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As for support, it's worth a try if needed, but I'm not optimistic.
I came to this product after CrashPlan's unfortunate decision to remove self-hosted cloud as an option (even as paid).
If the $29.99/yr. MSP360 Windows Desktop Pro version supports this approach and doesn't break things or require starting from zero, I'd gladly pay it. AND, a VPN accessed remote share would have to be recognized as LOCAL STORAGE (unlimited). I long since grew out of the 5TB limit.
I've not had consistent answers or responses from previous support emails on these questions.

THANK YOU for the quick reply.

Just lucky I guess. I do hope it's resolved ASAP. This is a great solution.

Now if I could only figure out how to make the client software see the revised HDD space on the remote side. But that might be a user error... investigating now.