I currently have XenForo installed on two different domains, one is my large live domain, and the second is one I am working on. When I upgraded both sites to Beta 3, I had an issue on only 1 site, which is kind of why this is strange.
On the large site, the TinyMCE editor was not rendering in the message quick reply area of my custom style. It was working everywhere else though.
Here are the symptoms.
1) Beta 3 - Large Site - TinyMCE editor not working on custom style.
2) Beta 3 - Large Site - TinyMCE editor IS working on default style.
3) Beta 3 - New Site - TinyMCE editor IS working on default AND style exported from Large Site and Imported.
I eventually downgraded the large site back to Beta 2.
What is curious is the actual source is different. The places where it was working, the TinyMCE editor was displaying in an IFRAME, but it wasn't in my custom style. At that point I thought it must be the style, but it was fine (and so was the source) when I imported it into the second site.
Anyway, I would like to upgrade to Beta 3, but don't want to redo the style. Any ideas where to start troubleshooting?