Hey Steve,
this a frequently reported fact and issue. The Cable Connectors used on Onefinity are the weak spot on the Onefinity (not the controller), especially in combination with the lack of strain relief on this machine. As someone who has assembled and troubleshot many computers, I can’t have a good opinion of such tin-plated connector contacts. The Onefinity CNC manufacturer addresses possible connector problems in this FAQ document.
The flimsy and error-prone connectors were inherited from the Buildbotics controller, of which the Onefinity controller is a hardware and software fork. They may seem annoying, but one should always keep in mind that professional, industry-standard connectors would make the machine much more expensive, and since the Onefinity CNC machine addresses hobbyists, the low price of entry is an important argument.
You can buy cable extensions but many people think that adding more of these error-prone connectors is not a good idea. Therefore from time to time, people request that Onefinity offers longer cables, but they won’t.
One solution is to make your own, custom length cables (howto crimping info is here), however you need to procure you a correct matching crimping pliers as they are specified here (scroll down a bit).
The cable extensions Onefinity offers are not longer cables, they are extensions to the stock cables.
This is a known fact. See monitor-life-saving workaround here.