It’s possible that you were blocked by a platform-wide issue with deploying apps from earlier today.
If you retry now, and it still fails, then it might be some other issue instead. In that case, I’d recommend posting here with logs that capture the problem.
In terms of problematic mount points, I’m reminded of this issue, where the volume’s path conflicted with run/ on the system (that’s probably not the issue but if it is, it’s an easy fix 
).
In this case you’d probably want to retry the deploy with LOG_LEVEL=debug, and include fly volumes list.