With all the talk about Mode Manager, and having only used the now "legacy" version in a very minimal way, I thought I would take a look at the current version. It was a bit of a bumpy ride. Not a major issue for me, but thought I would post it anyway in case it was something worth looking at.
My test/dev hub (C-4) was running 18.104.22.168 and produced this error when attempting to install Mode Manager:
I applied a HE platform update to bring it up to 22.214.171.124. When I accessed the Apps page I saw both the Legacy Mode Manager App and the new one I attempted to install earlier. When I clikced on the new Mode Manager I was presented with what I assume is the expected "upgrade" path.
I'll start with a new setup and play around some more.