Mac Mail App is "stuck" Moving Messages

I'm running Catalina 10.15.4.

My OSX Mail App has been stuck moving messages for a couple of days now. New incoming emails are also not being delivered to the mail app. (They are on my iPhone).

I've also noticed certain folders showing an unread message count, but the folder is empty or has no unread mail in it. The unread count badge also goes away temporarily but then returns.

See screenshots showing Empty Junk folder but with unread count.

I've tried the following things:

• Reboot
• Force Quit and relaunch
• Safe Mode
• Removed the com.app.mail folder from /Library
• Removed com.apple.MailServiceAgent from /Library

So far, no joy.