Per the subject, after the mail server upgrade, Apple Mail stopped running rules. Or at least, running the rules has no discernible effect on the inbox. I do not think this is a Dreamhost mail server issue, I think it is likely an Apple Mail issue, but I was hoping someone else has had this issue after the upgrade and figured out a solution.
edit: after posting this, I saw a note about Apple Mail in the migration guide:
However, that section is pretty vague about what exactly it means. Is it saying to delete and re-create all of your rules? Any help would be appreciated.
edit2: Now that I am looking at this in more depth, it does appear that all of the rules folder destinations got jumbled, and making changes to the rules seems to make them operational again. Unfortunately I have about 50 Apple Mail rules. I will triage them and report back if it fixed the issue or not. Thanks for hanging with me on this journey of discovery.