No Dual Screen on Mac 17.1 ?

Got a weird problem: While my system is seeing two screens and I can move my windows over, I can't activate Dual Screen mode in DR. It's greyed out. Strange thing, though, is that I can do a Clean Feed to the other screen. This is 17.1 final under Catalina.

I doubt it's the hardware, since I have dual-boot on this iMac for testing purposes. If I boot into Mojave and run 17.0, I can use dual screen mode as expected.

Anybody seeing this? Is it a problem in 17.1?

Bildschirmfoto 2021-03-10 um 13.14.52.png

Bildschirmfoto 2021-03-10 um 13.15.19.png

Are you by any chance in the CUT page (which is single screen only ) ?
Otherwise thry the UI reset option from the same dropdown menu at least 2 times. (one is sometimes not enough to fix UI sizing issues)

Are you by any chance in the CUT page (which is single screen only ) ?
Otherwise thry the UI reset option from the same dropdown menu at least 2 times. (one is sometimes not enough to fix UI sizing issues)

Thanks Glenn - I had the same issue as described by Uli on 17.1 running on M1 (obviously Big Sur) and your suggestion fixed it!
Cheers!

No, on the Edit page. But you are my hero now: Of course, I tried a UI reset, but not two of them in a row. That fixed it.

Thanks for not only making great software for controlling Resolve on the Mac, but even taking the time to help on this forum!

No problem. Happy you get it working again.
The reason i know this wierd fix is that i regularly switch to all kinds of resolutions to simulate all types of customer setups and since version 12.5 Resolve does not like it when you switch resolutions , or attach/detatch/enable/disable screens specialy when it is running. Sometimes panels are not properly resized or the bottom 3 panels layout gets stuck in 2 panels mode with wierd dimensions
So i found out that the 100% sure way to fix it is 2x UI reset in a row and in hard cases restart resolve after it and do it again.
There are even a few resolutions that are on the edge of just facilitating 3 vs 2 panes at the bottom that require this a few times plus a few reset to kick resolve back in shape. Stuborn little thing