Hey Nick,
I would check all the points in the help document “Troubleshooting: Rail is getting hung, stuck, or out of alignment” one by one.
Also note that cables not only fail on their connectors. A multimeter can help. Also be aware that neither Onefinity cable is made for permanent motion in a CNC. Sometimes replacing the curly Z cable, that can break internally, or retrofitting strain relief on the machine can help (or better retrofitting a drag chain system that runs cables specifically made for permanent motion).
Welcome to the forum!