Eventually found a solution: The actor holding my HISMs was spawned during the game, not already placed via the editor. Once I changed it to be placed in the editor, the crash was solved.
Still, the regular HSMs do not have that problem and I didn’t have a crash even when they were part of a spawned actor.
But in case someone else has the same issue, that’s how i solve it.
I still would like to know if this is a bug or a feature