Sorry to hear that bmalloy.
So after a couple of days I think I’ve found the issue. No solution as yet, but I do have a workaround.
It looks to be an issue with flexbox support in IE11 and changing vendor prefixes. More detail here if you’re interested.
Min-height and flexbox (flex-direction:column) don’t work together in IE 10 & 11-preview
I’ve tried a range of suggestions from this and other posts but no luck. In the end I added a scrollbar to the main content block.
#primary #content {
overflow: auto;
}
Because the text doesn’t overflow in FF or Chrome the scrollbar doesn’t appear which is great. It just affects IE and while not ideal, looks a lot better than the text running over the footer and down the page.
Not great if you’ve got loads of posts though so it would be nice to find a proper fix.