I’m still not sure what was causing the problem but it has stopped now. It was adding this tag – <div id="lipsum">
and then never closing it. So, instead of what I was showing before, with the more tag, it looked like this:
<div id="post">
<div id="lipsum">
<p>CONTENT BEFORE MORE TAG
(more…)</p>
</div>
So it was still missing a div and therefore breaking stuff. I noticed that at some point in my testing it just… stopped. I deleted the posts that still had it and now everything seems to be working. Strange…
I’m going to make this as resolved since it’s not longer a problem of mine but it would be nice to know what was going on and why it suddenly just stopped…