Hmm… let me look into this one. We are a version behind on Xenforo (the forum software) so could be related to that, not sure. We have avoided upgrading because we are happy with the current version and because when you upgrade it tends to break a lot of add ons.
Let me see if others using Xenforo 2.1 are having the iPad issue and if there is a fix…
Chris, I've posted a thread in the Xenforo support forums. I have seen that randomly over the years on my iPhone but it was related to the browser I was using to access the site, not the iPhone itself. What browser are you using and have you tried a different one to see if it actually is the browser?
"They need the toggle the bbcode in the editor, the [ ] icon."
On our site, the 'Toggle BB Code' button is a little gear icon all the way to the right in the options bar. It's very hard to see when grayed out so hover over it and you'll see the 'Toggle BB Code' text. Click it once and see if that doesn't fix it for you.