Hi,
Could you long press the account (in my app), choose Options and Folders, and check that this particular account's scheduled mail checking is enabled?
Could you also open the account's base Account Setup, then use Manual to advance to incoming server page, and check that it's indeed configured using IMAP, not POP3?
( FWIW, I've got my @gmail.com account on multiple devices, so I hope we're just missing some settings )