third display won't detect on mac pro, using Catalina update

I recently updated my MacPro (late 2013) to Catalina. My three displays I had hooked up worked fine, then today I replaced a wire to one of the monitors so that I am using all thunderbolt to HDMI on all three monitors. Once I replaced the wire, one of my monitors will not detect.

I can use the two monitors, but the third will not detect. I can unplug one monitor and get the other two to work, I can change the thunderbolt ports on the MacPro and they all work, all ports work, all monitors work, all wires work, but the computer just won't detect the third monitor.

I went to System Preferences, displays, and under arrangement hit the option key to display the "detect displays" button, but nothing. I've reset the pram by rebooting and holding option control pr, but nothing. I've shut down and unplugged the MacPro and all the thunderbolt wires, but to no avail.