I couldn't find a previous thread about this.
In any 6.5.X build i tested (2311X, 2365X, 2356X), in the Manila Mail Tab:
After setting up an account and syncing it the first time, the preview won't work anymore.
Meaning that "Send/Receive" will show you the "green number" on the top right, but the mail previews are not updated. Can't swype to bring them up either ...
Only changing tabs will "update" it
Never noticed it before myself honestly until a user pointed it out
Anyone who's got an idea?