We are opening ArcMap from a different process using the AppROT interface.
Then we run a class within ArcMap that create toolbars, add layers and does some other stuff.
The class is called from AppROT but is running within ArcMap to save the marshaling.
The class finished successfully. The toolbars exists in ArcMap. The layers that were added appear in the TOC but are not visible in the map.
Trying to refresh or turn on/off layers did not help.
The only solution is to save the MXD and reopen it – then everything looks fine.
It looks like the problem is somehow refresh the ActiveView.