Flagged emails not syncing between Mac Mini, iPhone and ipad

This issue has been bugging me for a while. I have just replaced my older Apple equipment, 2019 MBP and 7th Gen iPad with Pencil 1, with a Mac Mini and an iPad Air with Magic Keyboard and Pencil 2 as this combo much more suits my WFH and revised travel schedule. I also have a iPhone 13

The issue I have been running into is that when I flag an email on any of the machines it syncs with other two in the Flagged Mailbox ie same number badge and emails therein however this all goes awry when I moved the flagged mails from the inbox to the file tree folders. I keep an empty inbox. The Flagged Mailbox then stopped updating and messages disappeared from it even though they were flagged in their relevant folders.

After a long time of searching for a solution which included disabling and re-enabling accounts\mailboxes and all sorts of other time consuming advice to no avail I filtered the various mailboxes where the individual messages were filed on each machine to include flagged messages. Hey presto the Flagged Mail Box on each machine tallied with both badge counts and contents therein.

Therefore if you are having this problem then I suggest you take the following steps;

• Mark messages as flagged in your inbox. This should work across all devices.
• Move message to your preferred folder for it.
• Return to this folder after moving message to it and amend the filter (the inverted little triangle on the bottom left) to include flagged. Repeat this on all machines. You will only have to do this once for each file mailbox.
• Your flagged messages will now show up in all your Fagged Mailboxes.

I hope this is of use to anyone else who is having problems with this. It even works with my Google, BT & Outlook accounts so long as you file their messages in your iCloud tree.