We went through all this last year, with Sierra and Catalina:
viewtopic.php?f=21&t=105506And you apparently never got that working?
Since then, the question pops up occasionally, and I've updated my iMac to Big Sur and Resolve 17.1.1 and Eucon 2020.11.1.10, the latest that seems to be available. I did this some time ago, and verified it's all still working for me, but that could have been with 16 or a 17 beta.
I've drug out the Eucon panel again and set it back up. It still seems to work flawlessly for me with Big Sur 11.2 and Resolve Studio 17.1.1.
I've also opened Fusion and Final Cut Pro on the system, and switching between them and back to Resolve, it all continues to work.
And as noted in this thread, others have it working. Perhaps that indicates some other issue with your system.
How is the panel connected to the Resolve Mac? Connected directly to a Mac Ethernet port, or through a network?
Do you have the panel set for DHCP, or are you directly connecting it with a hard wired IP address?
Have you updated the panel firmware to 1.1.11.0?
In the Eucon Preferences panel, in Mac System Preferences, do you have anything entered?
Also, in the Eucon app, on the Assign tab, make sure the "Lock to Application" checkboxes are all checked. And that the application listed at the top is DaVinci Resolve.
If none of this helps, then as before, I am out of ideas.
Edit: And I guess I should add:
You have Avid Artist Color selected in the Resolve Preferences - System - Control Panels?
You are not using the Apple App Store version of Resolve?
You don't have any other computers on the network also running Eucon, that may have control of the panel (getting you the display rectangles), instead of the computer running Resolve?