Message admin extension won't load workflows from extensions
I spent ages trying to get our wmf workflow message to work with the Message Admin extension (I even renamed all the abbreviated variable names to words & added getters for all the abbreviated class properties so I could read the code without glazing over) and ... eventually I tracked it down.....
https://github.com/civicrm/civicrm-core/blob/master/Civi/Test/ExampleDataLoader.php#L80-L88
Normally I would say it's great to constrain things to core while things bed in - but in this case being able to define workflow messages in an extension is the main deliverable.