I just happened to be flipping between my dev server and production and notices something odd. I was missing teams for change notice and change request. Now Dev is straight OOTB 12.0.2 and my production has been updated since version 7 back when we used CMII workflows. Its not too difficult to rebuild but wondering if there was an upgrade step along the way that remove them or was it me accidentally deleting them. I could not tell you when it occurred.
Checking OIR rules, I can see that it was looking for a team called "ECR" for change requests and "ECN" for change notices. I do not use these OIR rules at the site level, workflows or lifecycles so nothing failed. It would fail if it tried. All my mapping is done at the Org or product level.
ECR was tied to CMII Change Request lifecycle and ECN was tied to CMII Change Notice lifecycle. From what I can tell, all lifecycles and workflows exist, old and new.
I wouldn't be able to help you with this but I can tell you that I have noticed some funky things happening between upgrades over the years. I can't think of anything off the top of my head right now but let's just say I wouldn't be surprised if the upgrade messed it up.