[Workflow] Iterator keeps on "running" and is blocked at iteration #5

[StephanieJoly4]

Bug Description

One of my workflows contains an iterator that receives 9 (not null) inputs but is blocked "running" after completing step 4. The data should all be in the same format so I have a hard time understanding what caused this and how to prevent this from happening after.

cc @martmull , this is the workflow we just edited and activated together