So I unfortunately just noticed that any subclassing of this resorts in the instances within an actor to be unselectable in the viewport of an actor. I’m using 5.5.4
The mouse will show the icon but they are completely unclickable.
Using a regular ISM does not show this behavior. It is easily reproduced. Create a BP of a ISM, drag it into an actor viewport, set a mesh and create any number of instances.
Enjoy the heartache. 