I have been troubleshooting this during the day and just wound up with an answer. I hope this helps. For starters I am using a dell XPS 15 9570 so hopefully this helps for mac as well. Here was my process (for every restart I did I selected the "shut down" option and then switched on the computer):
1. Uninstall universal control and remove the quantum as an allowed device in your thunderbolt settings.
2. Restart computer
3. Update thunderbolt drivers and computer bios/drivers if any.
4. Restart computer
5. Connect and turn on quantum and allow device to always connect (I think mac has a similar process as well).
6. Go to https://www.presonus.com/products/Quantum-2626/downloads to download the appropriate version of Universal Control.
7. Switch off and unplug quantum and restart computer. (I did not open Universal Control after it finished installing).
8. Connect and switch on quantum and open Universal Control (This was when I got the solid blue light that we all have been searching for).
9. Update quantum firmware if needed and follow the installer instructions.
10. Switch off quantum and disconnect and restart computer.
11. From here everything should be good to go.