27UL850 detected as 27MB85Z

[bernarius]

Sorry for inconvenience, but I am in desperate mood.. I installed BD on my Macbook M1 2020 to try with LG 27UL850-W. tried to use keyboad to control brigtness, hiDPI etc. Left for few hours, but after I came back and woke my Mac everything was ruined. Now my external display is recognized by Mac as 27MB85Z. Resolution and other things failed. Resetting, uninstalling BD do not help& Pleas help!

[waydabber]

Hmm. 27MB85Z sounds somewhat arbitrary. Did you ever have a 27MB85Z display connected to your Mac? The 27UL850 is a well known and widely used LG model, DDC control should work just fine with it, the 27MB85Z is a completely different display with different specifications. Is the display directly connected to your Mac?

[bernarius]

Thanks for your reply! No never had. Only this one for the last four years. The display is connected directly. I have just tried to connect it to my wife’s Mac air (BetterDisplay was never installed here) and it is also detected as 27MB85Z. So something in the firmware was changed.. Sorry for my stupid guess!

[waydabber]

I see. Maybe these displays share the same firmware and due to some kind of internal fault the display might be serving the wrong EDID. Try to do a factory reset if possible. If this does not work, this might be some kind of rare hardware failure :( - never seen anything like this though.

[bernarius]

I have managed to update the display's firmware (reset did not help) via an old and ugly LG utility. Everything is fine now!

[waydabber]

Nice, good to know, we'll leave this here for others with a similar issue.