1) Disable "Focus Assist" (new update that came with April update)2) Disable or uninstall Game DVR / Xbox app
3.- If you can switch screens, but it takes forever (longer then before the update), turn off every focus setting.
Full screen optimization should stay on for people with AMD graphics card using the Instant Replay function. Otherwise it will hard crash your computer (BSOD).
I dueled him once and was in control first half of the fight and then food buff wore out and not noticing lost, so he did win but hes by no means any better a player than I.
For the black screen when recoding, try enabling the record desktop option for relive. It fixed it for me.