It should be noted though that this isn't an "issue" per se (why it's simply a warning in FCP) The side effect of write cache being disabled is slower access to the drive(s).
I think Appdata backup will restart in the same order as what's listed on the docker page. Been a long time though since I did the coding, so could be mistaken..
Personally, I doubt this has anything to do with 6.7 If you found out via FCP, then it's simply that the test for this went in at the same time that 6.7 was released
Maybe I'm thinking that it was in NerdPack during 6.6, and I just left it installed for the longest time on 6.7-rcX @dmacias would need to update NerdPack
https://forums.unraid.net/topic/50490-solved-commands-to-start-and-stop-array/?tab=comments#comment-496967
But you'd first have to add in the csrf token to the end of the line ?csrf_token=xxxxxxxxxxxxxxx via whats listed in /var/local/emhttp/var.ini