Rules that continue to function beyond 24 hours and sync/apply across multiple devices.
I created several rules that would filter advertiser emails to automatically move from my inbox to a temporary archive. I also created a rule to empty out any emails in temp archive which are older than 60 days.
Things worked great until I launched Airmail on my iPad. Suddenly all my rules reverted so that every "moved message" was moved to the inbox. Even after I corrected this, none of the rules seem to be working or applying. It basically rendered all my rules useless.
Sure I can go back to creating rules in Gmail, but I'd prefer to create them in airmail because of the flexibility.