Apple Mail deleting emails as soon as they download

I've been having trouble with Apple Mail for a few months now. It's deleting messages before I even get to see them. I click on 'get mail', it starts to check and I see in the bottom left of the screen it will say "downloading 2 messages" or "downloading 5 messages", and then nothing. No messages download and they're not in my spam folder or any other folder.

I've removed all my 'rules' thinking maybe something I'd set there to deal with spam was blocking them. And even when I get someone to send me an email to see what happens, their email disappears too. I have several email accounts and it's happening to all of them. I can find the messages on the servers, but for some reason Apple Mail isn't letting them come through so it's definitely a problem with Apple Mail.

I only use my mac book pro for email, and I don't even check email on my phone.

I'm at my wits end with this because I have several websites and I'm not getting my business emails. I'm missing of emails to my personal address too.

I've been using Apple Mail for years now and never had this issue before I downloaded Sonoma.

If anyone has any ideas I'd be so grateful.