Found the problem. Had any of us looked at unity8-dash.log (attached) we would have seen it.
The problem is that MainView uses Ubuntu.PerformanceMetrics but that package is never installed.
Solution: sudo apt install qml-module-ubuntu-performancemetrics
So the bug is just Unity8 missing a hard dependency on that package which it requires.
Found the problem. Had any of us looked at unity8-dash.log (attached) we would have seen it.
The problem is that MainView uses Ubuntu. PerformanceMetr ics but that package is never installed.
Solution: sudo apt install qml-module- ubuntu- performancemetr ics
So the bug is just Unity8 missing a hard dependency on that package which it requires.