"With that many issues on different phones" of different makes but same browser, I'd recommend backing up your bookmarks AND UNINSTALLING OPERA for some other browser.
I did so on my wife's phone and - lo and behold - m.facebook.com works without issues.
Obviously last thing any Opera employee (cough, cough, Qihoo) wants is help us. It seems like some management is trying to make the $600 mil deal worth it for the new king on the throne.
So, forget it - Opera is no longer a browser - it is a Trojan horse invading your privacy. If it was some sane company, they'd have at least participated in a discussion that says loud and clear that their beloved software hijacks traffic.