Hello.

I marked 5 letters with different categories. Next I marked same letters with flags (to-do and completed). After couple seconds synchronization status changed from "Waiting for server response" to "downloading from server" and from 2 emails categories and flags disappeared.

If I mark these two letters either flag or category, it will stick. But when marked with both, both disappear.

I tried to mark with flag from webmail, same problem. I don't know in which way these 2 emails are different, but I suspect if I mark more letters with flag and category, they will not be only letters to loose category.