If your Juniper can pull an IPv6 and the other cannot, I would contact the MFG. Since the Juniper got an IPv6, then you ALSO know I provided you accurate information. T1 Agents at Cox are NO LONGER technically trained. They use a monkey script for everything, and if it's not in there, many just make stuff up instead of getting you to someone who may know the correct answer. It's unfortunate but Cox wants to provide Customer Service, not Technical Support.
That being said, we know,
- Juniper can pull IPv6 address.
- The Miktrotik router cannot receive an IPv6 address
I would go to the Microtik forums and look there or contact the Mfg, A LOT of people with your router seem to have issues with it and IPv6.
https://forum.mikrotik.com/viewtopic.php?t=151637