Using the basics of your setup above I’ve not been able to reproduce this on my end. 
I didn’t use any the branches that you’ve got setup and I applied the BP that spawns via the drop down on the Spawn Actor nodes as well.
When either the scaled cube or the regular cube spawns I have collision with my third person character.
If you have a sample project that you can reproduce this in I can have a look and see if something seems off.
Let me know.
Tim