Image Media fields seem to work until you try to insert the image into the field - i.e. clicking 'Insert into Field' on the media library thickbox. I see the AJAX call go through. But, the response part of things is always empty and the image is never inserted into the field.
On file upload fields I only get the error: 'You do not have sufficient permissions to access this page.' - There is no button to insert a file.
I tried loosening permissions on the mf_cache folder thinking that could be it - but that's at 775 (as is wp-content) with the same errors. Any insight?