It may also be worth your while to yum update the Cent7 box if you haven't already. There were some weird IPv6 --> IPv4 listener translation mumbo jumbos happening that didn't work properly in earlier versions of Cent7. Updating to the newest kernel fixes these in my experience.
After trying to update CentOS to latest version and trying to check other things, I finally figured out how to make it work. fprobe wasn't running at all before, and I needed to include -n option and choose the newest version instead of the default (5).
After trying to update CentOS to latest version and trying to check other things, I finally figured out how to make it work. fprobe wasn't running at all before, and I needed to include -n option and choose the newest version instead of the default (5).