I had the same issue. I am also using KLEO theme and end up with the problem where rtMedia upload button was not working in activity stream or even in albums. I searched everywhere and here I found that a solution to put some code in functions.php. I was about to test this problem, but somehow I managed to remember one problem previously I had with some other site , which was a Javascript Conflict issue.
And yes in my case it was Javascript issue. Not exactly it needs to be conflicted. If javaScript warning or error for any code of any other plugin or of your custom javaScript is there, which may not be related to rtMedia, but some other code, will make this rtMedia plugin fail to work. I added this reply so that users can look into this problem if having this issue before tweaking some code. Mine was a custom javaScript which was meant to put for one single page, but I put it in KLEO theme options general settings, for that reason this javaScript thrown an error for all pages other than the page it required. I just removed it from that place . After that this issue was resolved.