i just followed your screen shots and tryed out content visibility
using the groups,
i created a group called resellers
created a post, gave the short codes as you said
Only registered users can see this text.
added a pic in the post
addded a tex
see whats happening in the link below
prior to this, i tryed with pic also, same the text, the pic also poped up on to the top of the page.
the content is getting invisible in the post below, but its popping up