2018 Intel Mac mini second display not working

[astrocramp]

Since the Monterrey update, my Mac mini second display is not working via USBC. Worked fine for years, with one Dell U2717D connected by HDMI, and the other via USB-C to DisplayPort. I've searched the internet and can't find a solid solution to this, it seems if I disconnect the displays, switch them with different cables, it temporarily works then fails again. Also, the "detect displays" feature in displays doesn't seem to be working either (the button doesn't even show up when I hit the Apple key).

Any ideas?

 

[Fishrrman]

"with one Dell U2717D connected by HDMI"

Is that HDMI (Mini end) to HDMI (display end)
????

Have you tried:
HDMI (Mini end) to DVI (display end) -- if the Dell has a DVI input.
(you may have already tried this)

On my own 2018 Mini (only one display), I was having the "black screen at startup" problem using HDMI-HDMI. When I changed to HDMI-DVI, it was fixed.

There's now a Monterey 12.1 beta out.
You have to sign up as a developer to get it, however (free).

 

[astrocramp]

"with one Dell U2717D connected by HDMI"

Is that HDMI (Mini end) to HDMI (display end)
????

Have you tried:
HDMI (Mini end) to DVI (display end) -- if the Dell has a DVI input.
(you may have already tried this)

On my own 2018 Mini (only one display), I was having the "black screen at startup" problem using HDMI-HDMI. When I changed to HDMI-DVI, it was fixed.

There's now a Monterey 12.1 beta out.
You have to sign up as a developer to get it, however (free).

No, I only have HDMI to HDMI and then TB to DP cables. I ordered a TB to HDMI cable, going to try that next.