New iPhone 16 Pro; Gmail emails won’t move into folders

Since switching to iPhone 16 pro, I can no longer move emails into my folders.

At times the mail app won’t display the messages and at other times when you click on a message it shows the previous message.

I’ve rebooted loads of times, closed down the app & restarted it which works one time for moving to folders or showing the correct email.

I’ve checked the settings and ensured the emails aren’t set to archive etc., I've signed into my gmail accounts on google & checked them, I’ve checked my network connection , I have the latest iOS.

Please help! Thanks in advance