> For years apple mail on iOS would always show 1 unread message in "all mail" for gmail. Just in case you are still seeing this, I had a similar issue that tu

> For years apple mail on iOS would always show 1 unread message in "all mail" for gmail. Just in case you are still seeing this, I had a similar issue that turned out to be a bug in Gmail and how Google put old Hangouts (or perhaps Google Talk?) conversations in your mailbox. Some very, very old conversations of mine were for some reason marked as unread, and this was showing up on the iOS unread count, but not the one on macOS.