My images aren't set within the content, it's called via custom fields. So I figured I would edit my feed-rss2.php file and call it from there. Placed the code and checked the feed via Firefox RSS reader and nothing.
After two hours of nothing, I had the bright idea of checking it on Safari's and IE 8's RSS reader, lo and behold something worked in IE that didn't work in Firefox, Safari... everything works in Safari.
It's not just images via custom fields that don't show, text custom fields don't show either, again they show in IE8 and Safari.
Anyone else have this issue? Nothing I do even seems to change the outcome in Firefox's RSS reader apart from deleting the entire code the feed goes blank, at least I now I'm editing the right files :P.
Sidenote: I've check other sites and images do show up in Firefox's RSS reader, the only variable I can think of is they aren't using custom fields to pull the images, but looking at the source code it's no different from how the images are pulled on my feeds.
Any ideas?