@Technicians Our engineers believe they traced the problem to a caching issue. They flushed the cache. Try again, and let me know if that fixed the problem. If so, we can better implement a complete fix.
Thank you for bringing this to our attention!
Update: we are working to improve our caching mechanism to minimize the chances of this happening in the future.
To help you diagnose this in the future: if you are searching for something in Workflow Builder and can’t find it, then ask yourself when the item you are looking for was created. If it was created in the last hour or so, it is possible the cache is out of date. The cache refreshes automatically in time, so if you are patient the item should appear. If it doesn’t, please reach out, further investigation would be needed.