I am trying to limit access to viewing actual K2 items to registered users, but I would like all users to be able to see the category listing view. The goal is once a guest clicks on an item in a category view they will get a pop-up prompting them to login or register. I have looked at a variety of different plugins and work arounds and can not seem to make anything work. HELP!

you can use the joomla access level to do that.

When using joomla access levels the item no longer shows up anywhere including category listings unless you are logged in. I want the public to be able to see the category listing, but have to log in to view the actual item/article.

Try this:

extensions.joomla.org/extensions/access-a-security/site-access/content-restriction/24225

I have tried this extension but the login is not popping up. I am not sure if there is a conflict with something else I am running, support is in Chinese and very limited. I thought this was the closest thing to what I am looking for, but it does not seem to work.

Any luck in solving this one. Before when I was using Version 2.7.1, i can list the restricted item in category view, but now I am in Version 2.10.3, suddenly it doesn't work