Ubuntu 20.04 - Second monitor doesn’t work, Ubuntu detects it

I install Ubuntu 20.04 to my iMac 27 2013 later. Graphic card - GeForce GTX 780M
When I try live usb two displays worked.
After installing ubuntu works only with apple display, Dell 21" display nothing but in settings it is showing.

my nvidia-bug-report.log.gz:
nvidia-bug-report.log (201.1 KB)

thank you!