Gmail notifications only appearing for some accounts
I have several gmail accounts, a couple of which I only use occasionally (for software/site registrations, purchases, etc.), and as such I remove them from my phone, a Galaxy S3, when I'm not using them. I have the latest version of the Gmail app installed and until recently whenever I added one these accounts back in notifications worked fine, but recently I don't get notifications for either of these accounts.
I've been into Settings and both accounts are set up for sync as all of the others are, and the notification settings are consistent across all accounts. I've set up another account and added this, in case it was something not being picked up for accounts when they are added, but this receives notifications fine.
Apart from changing one of the accounts recently from POP to IMAP I have made no changes to the settings on either of these accounts on the web, and anyway I'm discounting that as one of the regular accounts I have on my phone is also set up as IMAP and all notifications for that one work fine.
Re: Gmail notifications only appearing for some accounts
You may want to try removing the email accounts, then adding them back again.