I would need to test this out a bit, but try wrapping your entire workflow in an APP Step, it may be a permissions issue
Edit: Please also try placing yourself in a group that has EDIT or Contribute permissions as well. Sometimes the workflow can be finicky and not function properly, even if you are a site collection owner. I have seen this happen before
For anyone having similar issues: I fixed the issue. It turned out that one Timer Job was stuck in Pausing and caused one of the Servers to spike up to 100% CPU which then ultimately caused the Workflow to be stuck.
Disabling the failed/stuck Timer Job and enabling it again brought Server CPU down to around 20% and Workflow has been completed in 2-3 minutes ...