macOS 10.12.4 beta 3/4 break external DVI monitor support

Number:rdar://30786721 Date Originated:3/1/2017
Status:Open Resolved:
Product:macOS + SDK Product Version:10.12.4
Classification:Serious Bug Reproducible:Yes

I don't know how widespread this is, but it's 100% reproducible for me.

Since at least macOS 10.12.4 beta 3 (and still happens on beta 4, wasn't able to check previous betas) my external monitor no longer works.

My MacBookPro (Retina, 13-inch, Mid 2014) no longer connects to my HP w2207 monitor over mini-display port to DVI.

I thought it might be something with my cable, but I'm able to boot into 10.11, 10.10 and 10.9 and this same machine works perfectly with that monitor with no changes.

Sorry I can't be more help—not sure how to debug this any further.

Steps to Reproduce:
1. Connect MacBook Pro to monitor over mini display port adapter to DVI
2. No signal
3. Reboot to any other macOS, it works as expected

Expected Results:
MacBook connects to external monitor

Actual Results:
Screen is black. Usually what happens is my MacBookPro kinda "flashes" once or twice while the connection is switching over. That isn't currently happening, I plug it in any nothing happens.

macOS 10.12.4 Beta (16E175b)

Thank you! 🤓

Happens in 10.12.4 beta 3 & 4, haven't seen it anywhere else. Night Shift is disabled, which is the only new thing that might be related. 



This is still happening as of 10.12.4 Beta 7 (16E191a).

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