I just found this thread as well. I having been dealing with the SHFS problem for the last several weeks about every other day. It required a hard reset to clear. My server is currently in this state and I was trying to troubleshoot the situation. I found a couple of things:
1. The CPU load on my dual Xeon 2.0GHz 12 core/24 thread is climbing steadily and at about >=30.00, certain Docker containers become unusable
2. If I SSH into the server and try to do any dick I/O in the /mnt disk structure (except for /mnt/cache/appdata), the terminal session locks up and has to be killed.
3. The CPU usage in UNRAID is still within normal levels (<=25% CPU) while there are a few individual cores that are peaked at 100% and do not go down.
I am going to hard reboot the server and make this change in all of my Docker containers to see if this alleviates my issues. Thank you for the recommendation.