Emails in Mac Mail folders and sub folders not syncing to iphone and ipad

I've set my email accounts up as iMAP on all my devices (mac studio, iPhone and iPad), set up folders and sub folders in mac mail on my mac studio.

The emails are not syncing to the iPhone and iPad. I have rules set up on my desktop mail app and when emails come in they usually get moved to a folder or subfolder or subsubfolder.

• I can see the top level and second level folders on my iPhone app.
• I can only see the top level folder on my iPad and none of the second or third level folders.
• My web mail has all the folders showing correctly and emails are moving in there correctly.

But... My emails are syncing to the folders on my iPad and iPhone. They disappear.

What else to I need to do when I set up the email accounts on my mobile devices please? I've tried to research this but found no information.

Thanks!