(.Net version is actually 4.6.1.)
When trying to load a view using Prism View Discovery (View Injection ends up with the same problem), I get a KeyNotFoundException, as the Region I am trying to load the view into does not exist, even though it was registered in the RegionManager during the initialization.
This used to work perfectly with Actipro 15.1.
This is a critical issue. I (obviously) really, really need to have this working. Note that I cannot use the legacy dlls.