Applying the Explosion particle effect to the tank worked fine.
Applying the Explosion particle effect to the tower blueprint however did not work. I had to actually go into each instance on the board and also apply the change.
My expectation would be that changing a blueprint should apply to the children already created. I did shut the editor down and compile and restart and that did not fix the issue.
The only fix was to manually apply the change to the instances on the board already.
Is this a known issue with UE5?