I think a Delay with value 0 after you’ve added all your HISM instances ought to do it. Small 1-2 frame delay should go unnoticed for the most part.
Interesting suggestion.
I previously inserted a [Delay] node (testing from 0.01ms up to 1000ms as a [ DoOnce] call on the [Event Tick] and also on the Event [Begin Play]. Unfortunately, it didn’t make a difference.
However, I didn’t think about adding the delay ‘just after’ the [Add HISM] call itself.
It’s worth a try. I’ll give it a go and report back.