A group containing 2 objects with erase blend mode, changing/hovering over some of the blend mode options for only one of them will cause designer to crash
Select one of the circles in the group. Try to change the blend mode to "normal".
It does work to change them both to something like "normal", and then change one of them back to erase. But changing one of them when both of them are erase will crash.
Crash Bug.afdesign