"Black" monitor screen when waking (MacBook screen OK)

Glenny2lappies

macrumors 6502
Original poster
Sep 29, 2006
495
116
Brighton, UK
Have a Cinema display connected via an Apple Thunderbolt to USB-C adapter connected to MacBook Pro 16".

When waking it intermittently doesn't switch on the monitor, i.e. the screen's blank. The MBP screen is awake. Only option appears to be to disconnect the Cinema display, but that can be a real nause if the Time Machine backup's running (the external hard disc is connected through the Cinema display).

I use separate spaces. The main display is the external Cinema Display monitor; the secondary is the MBP (e.g. running IM, messages, Music, Amazon Music...)

It's happened a few times and really is annoying if the backup disc is mounted -- especially if TM is running -- where I have to start finder on the MBP screen to eject the disc before I can disconnect the USB-C connector.

I've a slight suspicion that it's related to full-screen applications on the MBP, but not sure about this. It's as if Catalina's doing it's stupid Spaces trick of showing one monitor only when full screen -- which is the reason for using separate Spaces.


Has anyone else had this problem?

Is there a command line spell I could cast to "reset" or "wake" the external monitor? (It's not the monitor, it's Catalina not displaying the screen!)
 
Last edited:

tommiy

macrumors regular
Dec 11, 2015
186
51
There is alot of issues with external displays on Catalina. I would not be surprised if this is just another one to add to the list. Fortunately I have not experienced this one but the 4 other issues regarding resolution being wrong on wake, continuous polling when asleep, setting internal retina display brightness to maximum when connecting external displays are all issues that drive me to frustration and need manual work arounds by the user each time. I've not experienced the colours being incorrect as some have reported but I just cross my fingers on that one. The solution with Apple with all of these is primarily manual disconnection, and/or user intervention unfortunately. I tried lodging a case with Apple and they accepted it and now it is mysteriously closed with no outcome. I may try again. Each . release external monitor support gains more bugs....sorry i don;t have a fix for you other than what you are already doing...
 
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Glenny2lappies

macrumors 6502
Original poster
Sep 29, 2006
495
116
Brighton, UK
My colours also change, sometimes flicker. I think this is nightshift being overexcited.

Catalina is a real dog's dinner. Hope apple aren't sitting there licking their nads.
 
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