to me, it looks like it’s “timing out”, maybe the workflow is too heavy to it to finish without a problem… it doesn’t really need to reach max capacity.
“The general rule is, change list of things is fast + good for relatively small (say, 100 items or less) lists. API workflows are a little slower to get through, but they are more scalable and reliable for large lists… if you have a change list of things operating on too big a list, it might time out / fail to finish and break the workflow.”
Phrase took out from the post: