Guys I’ve the same exact problem. I also wrote you an email but nobody is answering me so far… I need help.
Same problem, both sad and frustrated 
Is the 2nd one still working?
It is, used it all day 3 days so far this week about 10 hours a day and no issues, so that is 4 total days of use now without issue (1 Day before Christmas also).
Thanks a lot for your answer! I have the issues you had with the 1st one… Trying and hoping to solve it
@Gary Z,
Thanks for the reply.
I confirmed that I am running the 10.12.2 Sierra update.
I disabled WiFi, and I am still getting the charging / not-charging (repeat) continuously. (Note: this is with the plugable UD-CA1 included USB-C cable. again, if I use the Apple cable then charging works continuously, but no docking station function other than power.)
Thanks for confirming the update and the behavior with wi-fi disabled. Can you please email support@plugable.com so we can arrange to send you a replacement cable to see if that helps? (We’ve had good luck with this approach on the few we’ve sent out thus far.)
@Lorenzo
It looks like you worked with Josh via email and a replacement cable is on the way. Look forward to an update after you’ve received it and had a chance to test.
Thanks!
@Gary Z
Thanks, I will contact support@plugable.com.
I did try the UD-CA1’s included USB-C cable with the Apple-Charger/Laptop.
That worked just fine. Very simplist testing, I know…
Thanks Ben! Looks like Josh has a cable on the way to you after you emailed in, so looking forward to hearing how it goes.
Also, appreciate the note about successfully using the provided cable with the Apple charger. When we’re seeing the interference, it seems to happen in scenarios where power and video/USB data are being sent over the same cable. In scenarios where just power or data or video are being carried, all seems to be well. So we appreciate the additional testing data that seems to align with what our findings.
So, had great luck with my second dock, used it for nearly a month without issue. Ordered 2 more as we would like to use this as our company docking station for the new mac’s as it is the best design out there. The first of the 2 new ones worked for about 7 hours and then started having the power on off issue charging the mac. Decided to play switch around with the 2nd doc changing out one thing at a time and no combination of cables would make it work again. Switched the dock out to the other new one with all the cables it came with and it has the power issues immediately. I will email support and try another cable to troubleshoot, current running an apple adapter also plugged into laptop and all works fine with the extra juice.
I have had the same problem come up. If I turn the Macbook Pro off and let it charge. Once it’s charged up, it works like a charm. I haven’t tried swapping the cables yet.