I know this is a 2018 article, but it's 2020, but for those of you who are looking for help, here it is. I just got my Quantum 2626 today, and was having the same problem. I resolved the problem by uninstalling the UC, and reinstalling it.
Then when I opened up the UC, it took a while to find the 2626. Once it found it, it showed it needed a firmware update. I updated the firmware, and once updated,
I followed the instructions and shut off the 2626 and disconnected the Thunderbolt cable for 10 seconds. I then reconnected and turned it on. Blue light was continuous. I then shut off the UC app and got back into it. It again took a while to find the 2626, but found it. I got back into Logic Pro X and found the drivers. Works beautifully.
My takeaway: It takes a while for the Universal Control Surface to find your new hardware, and then you will need to update it. It will take a while to find it again, but will connect and you will be all set. At least that's how it worked for me. I hope this helps.