@priel71 Another quick update re bios raid on system disk installs such as yours.
Regarding my previous comment:-
As of 3.8-11.11 testing channel release the “wipe me” cogs no longer appear on mdraid members (screen grab).
I know you are currently on stable but as the current testing channel is now 25 days or so old the next stable updates release is pending. Just a heads up that these issues are getting addressed and that they should hopefully fall into place on your stable channel systems with the next release.
How are the 3 reluctant pool members doing, have they stayed put after that last reboot?