IPhone – “No offline messages” message after logging into Gmail on iPhone and iPad (using same account)

[Note: Cross-posted to webapps.stackexchange.com]

My wife and I have 2 iPhones and 1 iPad2. We each use our iPhone to access our Gmail accounts. My wife also uses the iPad for that (whereas I do not).
However, recently, my wife is unable to access her emails on her iPhone or iPad.

To be clear:

• She can login to Gmail without a problem.
• She has access to the Internet at all times (this is regardless of being on 3G or WiFi, the problem is the same with both).
• She can access other Google services (e.g. Google+) from the same device.
• She can see how many unread emails she has in her inbox.
• Logging into the Gmail account from a computer gives no problem at all.
• Gmail is accessed through Safari (on the iOS devices).

But, no, she does not see any email in her inbox: she only has the message "No offline messages".

This occurs on both devices: her iPhone and her iPad.
Google tells me that she is not the only person to have the problem: it has happened to people on iOS, BB Playbook and even in Chrome. See links:

• https://discussions.apple.com/message/17984389?tstart=0#17984389?tstart=0
• http://forums.crackberry.com/blackberry-playbook-f222/gmail-no-offline-messages-667628/
• http://www.flickr.com/photos/nda/6106404220/

The only solutions offered were on the BlackBerry forums such as:

• Clearing cache (no effect)
• Viewing Gmail in full browser/HTML mode (not possible from iOS)[correction: this is possible, one needs to scroll down to the bottom of the message list]

I personally use the Gmail specific app downloaded from the AppStore. So I downloaded that for my wife and tried that. It suffers the same problem.

• I tried logging out of her account and logging back in, to no avail.
• I tried shutting down all the apps and relaunching them, to no avail.
• I tried shutting down the devices and restarting and relaunching, to no avail.

Finally, thinking it may be specific to my wife's Gmail account, I tried logging in with my account and it suffers the same problem of that device, although not on my own iPhone.

To make it even more complicated, I logged out of my account on my own iPhone and logged into her Gmail account. There again, no problem to log into the account, but "no offline messages" is still displayed.
I then logged out of her account and switched back to my account (still on my iPhone) and I can access all my emails without a problem.

Any help would be greatly appreciated!

[Update:
The Gmail.app and accessing the account through Safari, on the iPhone ONLY, is now working again.
However, on the iPad, it still does not work.]

[Update2:

1. It is possible to view the browser/HTML version of Gmail and in that case it works. However, this does not solve the mobile view problem.

2. In the mobile version, I noticed that if one selects specific tags, the emails are shown. The problem is when viewing "Inbox", "All messages" and other default groupings.]