I created the following automation following some examples I found on this forum. The automation aims to set the fixed version on all child tickets of an epic to the same value as the parent epic.
As you can see from the log, I'm saving the Epics fixVersion in a variable and logging that variable to confirm it worked. Then I start the For: Stories to loop over the child tickets. I'm again logging the value in epicFixVersion. Finally, it logs that it has successfully updated all of the tickets in the epic.

I'm setting the Fix Version with this action:

The logs look good. The automation seems like all the others I've seen, but the child tickets aren't changed.