External monitor not waking when starting 16" MBP or exiting sleep


macrumors newbie
Original poster
Mar 7, 2012
So I've got 2 2019 16" MBP's (one personal, one work issued). One with the 5300M, one with the 5500M. Both experience the exact same behavior with different Dell/Alienware displays connected via DisplayPort through different USB C hubs (CalDigit TS3 Plus, an Anker and a VAVA hub). So I've got diversity in the hardware here. In one case there's an IOGear KVM switch, in another there isn't. So that's not the point of failure either.

Monitor's on, USB-C hub has power. Power up laptop... doesn't see the external display. Unplug and plug back in USB-C hub and bam, everything is seen. If computer goes into standby, same behavior. Both laptops do this. Doesn't matter the monitor or hub of choice, if there's a KVM switch in between or not, etc. etc.

Both running 10.15.3 (19D76).

Anyone encounter something similar? Given all the hardware I've used and reproduced it with, this seems like it has to be software somewhere.


macrumors member
Jun 10, 2011
Had the same issue with my 2018 Mac mini and now 16" MBP on a Dell monitor (also DP to USB-C adapter). Best fix for my mini was to just prevent the computer from sleeping when the display sleeps (option in power settings). Not as good of a solution with the MBP as the dGPU is constantly sucking power even when the display goes to sleep I believe.
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