I'm running IE Mobile on my Windows Phone 8.1, and all morning I've been having problems with editing posts. I can post from my phone; but when I try to edit, none of the "Save" or "Go Advanced" buttons do anything. The text box is a funny size now, too: It's shorter and doesn't extend all the way to the right. I tried clearing my cache and logging in again, but the problem persists. I'm posting in this thread because of the likelihood that it's related.
Hopefully the problem will be resolved when AT&T gets off its ass and approves the Windows 10 Mobile upgrade for my phone, which will come with a better browser.
EDIT: This post is being made from the MS Edge browser on my tablet. There's no problem saving my changes when I edit.