Thanks for posting this! It seems to be working again, and I’m very happy about it 
I won’t mark anything as an answer yet, because (at least at my local setup) it still feels like I need a little bit of voodoo rituals to get everything in working condition. I didn’t get the error
Could not evaluate form: (cljs.core._STAR_print_namespace_maps_STAR_ = true) [ReferenceError: Can't find variable: cljs]
but still it only worked correctly after restarting the REPL after metro has been started.
Let’s hope that in the future we can either completely explain the cause of the issue, and/or pinpoint more accurately what component is causing it. Last week it felt to me as though the main process worked correctly, but that the REPL just “didn’t get the memo” that all was fine and hence kept waiting for the connection. But I currently lack the experience (and motivation) to dig deeper into that. Perhaps in a couple of weeks/months I’ll revisit the problem.