Big Sur and RX580 eGPU - No Video

I had no trouble running season 21 on my 2018 Mac mini i7, Catalina and RX580 eGPU. Unfortunately, Diablo III loads only to a black screen with an oversized arrow cursor and audio with the same hardware and Big Sur. If I disable ‘Prefer External GPU’, Diablo will load to the menu screen but with the expected performance hit. I have deleted and reinstalled Diablo III with no resolution.

2020-12-07
Issue still present on version 2.6.10.71814.

2020-12-14
Well, it worked for a moment… I installed a new monitor tonight (upgrading from ultra-widescreen to 2k). When I launched D3, it opened in a window and displayed properly with the eGPU enabled. When I changed the display to Fullscreen and relaunched, I was back to the black screen with oversized arrow icon. Obviously the issue is resolution-related, but I just cannot find the right combination to get it to work…

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Exact same issue here- D3 working fine before I installed Big Sur.
RX580, eGPU. I get a blank screen with the cursor on it, the game sounds are happening OK but nothing else on-screen :frowning:

Have tried setting the game to launch in Windowed mode but the screen is still blank if the eGPU is set to be preferred.

Update- I connected a dummy HDMI connector to the RX580, set the displays to mirror and it started working.

Aaand much like OP’s experience, after I disconnected and reconnected the eGPU it no longer worked.
Had to reset the mirroring/scaling options to get it to work again.

I’m having this same problem with multiple games (and have been for a while). Very frustrating, since the egpu was working fine for a full year… and then I updated to Big Sur. Did anybody find a solution that works for them?