Since February, at random, during e-mail conversations, messages (the entire thread) dissapear from my mailbox. After a month of support calls, with no resolution, I discovered that these e-mail threads have been redirected to my Account/Trash/Recover Deleted Items container. To see them, I must move them to a folder within my account. Once this is done, I can forward them to a seconadry account and see them as well. As a bonus, while in there, I discovered emails that I had never seen before. People were saying that the sent me e-mail and why I never replied.
The first time this happened to a secondary account. It took over a month for support to resolve this issue. They said it was due to the February e-mail migration and the had other customers experiencing the same thing. It went to engineering. Now a month later, I have the same issue on my primary account. This time it's been two weeks in with Executive Support and they punted it back to Advanced Repair who are now saying it's an Apple issue.
I am running High Sierra 10.13.3 and iOS 11.2.6 I have no rules setup in my Apple Mail client, both devices. There are no rules setup in any of my Xfinity mail accounts either. After 3 attempts today the support person was cut off (Xfinity VOIP) and sent me back to Advanced Repair to re-log the issue. Anyone have the same issue? Everything was fine for years until the e-mail migration in February this year.