Spawn Actor from class: Actors get immediately deleted after spawn

I have in my PawnBlueprint an Event which is called every 2 seconds. It executes a function which spawns 36 Blocks, with a "SpawnActor from Class"Blueprint and a ForLoop LastIndex 36.

The problem, after some time ( always the same time ) they just get deleted immediately. You can see them appearing and disappearing extremly fast.

I have checked every blueprint which has something to do with the spawned actors and tried many things with removing functions and DestroyActor Blueprints and using Print string to see if something changes, but nothing helped.

I am working on this problem for 6 hours now and I can’t seem to find the problem and I start to believe its because theres somewhere something engine internal deleting my spawned actors.