Hello, hopefully someone is still around that has an answer to this. I'm having this exact issue as well, just freshly installed ClearOS 7.2, coming off of 6.6, I verified my clearos-updates are enabled, and even ran that line just to be sure. I can go through the marketplace and mark up a bunch of apps to install, then hit Install Selected Apps, and it will just drop and say that no apps were selected to install. Very frustrating!
Anyone have a fix for this? My output from yum repolist is: