Mac Pro mailbox has different amount of emails than iPad and iPhone

I have seven gmail accounts and two accounts that use my own website name xxxx@xxxxx.com that use IMAP.

The number of emails on my Mac Pro for ALL INBOXES is 530 and my iPhone and iPad are both 484. I have compared all devices and each email has the same number of emails in all the different categories. I can't find the discrepancy.

I have tried syncing as well as turning icloud off and on again on all three devices and then restarting each device. I also ensured that all the mail options are set the same on each device.

Why aren't they syncing?

Thanks so much!

[Re-Titled by Moderator]