Knowing what the issue is, it's seemingly impossible for any 5,1 user to not be affected by this issue. Glad you're finally off the "I'm the exception" list.
I've been running
11.4 since May 25 on my 6 core 2010 Mac Pro using Martin Lo's OpenCore 6.8 package. I've been oblivious to this thread (thinking it was only for folks with blade SSDs) and was also running 11.3 with no discernible issues.
I leave my 5,1 running continuously and only restart occasionally. Once every 1-2 days. [Also my original airport wifi is disabled in network preferences. Only my Edimax AC1200 USB dongle is enabled and first deviceo using these drivers--->
https://github.com/chris1111/Wireless-USB-Big-Sur-Adapter )
When I installed
11.4, it seemed like a fairly smooth install. I booted right back into OS after the long update.
So I went ahead and proceeded to clone my main internal SATA SSD drive with CCC with my
external eSATA dock
Weird thing since 11.3
: I could previously, power the eSATA dock on or off even while the Mac was running with no issues after ejecting/putting aways the drive from the desktop.
Since 11.3,
after ejecting the drive and removing it from the dock and then proceeding to powering off the eSATA dock, the
OS complains that I didn't eject the drive properly.
Also I found that since 11.4,
I can't leave the external dock powered on with
no drive in place while rebooting. It will definitely hang my restart.. I never get to the boot picker in Opencore.
If I keep the dock powered off the restart proceeds normally.
So if one doesn't need to restart that often.... it appears to me that 11.4 is viable for my purposes?
I also tried dumping the ROM and check to see if I will have issues. I've used the ROMTool previously, but decided to look again and reinstall it along with that helper. I also did the super 5 time NVRAM reset. (It seems the garbage collection is working--dunno.)
But I did have
one stuck reboot after the doing this--which I "blame" on the RomTool helper and the 5 time NVRAM super reboot.
I had to do another 3 NVRAM clears and then the unit booted up normally. It's been fine since. I've rebooted 2 or 3 times since yesterday with no issues. So a warm reboot seems fine to me.. I haven't done too many cold reboots as I generally don't shut it off.
Anyway.. this is my report.
My set up is in the signature.
UPDATE: Removed the incorrect screenshot from this post.