why are my flagged emails not syncing across devices

Thank you for your answer.

The out-of-sync flags in Apple Mail stemmed from my use of labels in Gmail. Once I removed those labels in Gmail my flag counts were reconciled between all my Apple devices.

Thank you for the suggestion. The out-of-sync flags in Apple Mail stemmed from my use of labels in Gmail. Once I removed those labels in Gmail my flag counts were reconciled between all my Apple devices.

Thank you,

Jerry