Can't boot Mojave on Mac Pro after Time Machine restore

My 5,1 Mac Pro is running Mojave 10.14.6 booted from an onboard SSD, an APFS volume. My Time Machine backs up to an onboard HDD also installed on the same Mac. There are no RAID drives nor any special boot configuration involved ... pretty much a "plain vanilla" setup.

Yesterday, while sorting through some old apps, I mistakenly opened one that did not play nice with Mojave and froze the finder, requiring a hard reboot. After the restart, the OS seemed sluggish and a couple of regular apps the were open during the crash seemed to have been corrupted. I decided the best course was to perform a full restore from the last Time Machine backup made before the crash.

I booted into the Mac OS Recovery drive, selected the appropriate recovery point and target drive, and let it run. After it completed several hours later, I get the error message when I try to boot from this drive:

"You can't change the startup disk to the selected disk.

Running bless to place boot file failed."

From the posts I've found on this error topic, this seems to be mainly an issue when converting from HFS+ to APFS or moving to a new drive, new OS, etc. Here, I am simply trying to restore back to the same, original drive with its original files, on the same Mac, no change in file structure or OS, so I think this should work as Apple intended.

I will try this again from a different recovery point, but I'd appreciate any thoughts on how to navigate around this glitch if there is some special trick needed. Thank you!