Mail sync read/delete one direction iPhone/Macbook

Greetings - I have a MacBook running Big Sur 11.6.8. All fine until I upgraded iOS devices to 16.2. I have 2 email accounts - one icloud, one Exchange/Outlook. The icloud account is working as before update - in other words, perfectly. For Exchange/Outlook account, now mail only syncs in one direction. More specifically, a new email appears on both devices but if I read on MacBook, it doesn't show read on phone. If I read on phone, it does show read on Mac. If I delete on Mac, it doesn't delete on phone, etc. How do I address this, please? Tried everything in my wheelhouse. Thank you!