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sniffs

macrumors regular
Original poster
Jan 24, 2013
190
6
So I use both thunderbolt ports on my Macbook Pro Retina for monitors.. on Friday of last week it was working fine, MacSierra 10.12

Sometime on Saturday I installed the 10.12.1 Public Beta 1, everything seemed ok until I came into my office and plugged both monitors into the 2 Tbolt ports.

My Left monitor never turned on. I unplugged and re-plugged a dozen times, nothing. If I unplug the active right monitor that is working, the left monitor turns on. This doesn't appear to be a hardware issue at that point. I boot into diagnostic mode and both monitors work. It generates a VFD002 error which I send to Apple.

Apple issues out 10.12.1 Public Beta 2 which I HOPE fixes the issue, nope.

So my left monitor no longer displays when plugged in. If I unplug the right monitor the left one turns on. If I plug the right monitor back in it never turns back on. If I unplug both monitors, I can plug either one into either of the 2 tbolt ports and the ports work perfectly fine.. it's just they don't work when 2 are plugged in. I've tried resetting NVRAM and SMC, nada.

EDIT: TL;DR - Both ports dont work simultaneously. I can plug my right monitor individually into either port and it works. I can plug my left monitor into either port and it works. If I plug both in, only 1 works.

Anyone else have this odd issue?
 
I did, the Public Beta 2? Yeah I installed that and it didn't fix the issue.
 
Working fine here with 10.12.1 beta 2.

Screen Shot 2016-09-28 at 8.08.43 PM.png
 
Nice, at least there's a post on their forums now so they are aware of it. I hope it's fixed soon.. Been using Beta's for awhile now and never once experienced a straight up broken feature like this before.
 
@mike666999 I have the exact same MBPR as you. I'm wondering if it only affects these models with the ATI M370X cards?
 
It did which is odd.. I have a few other Mac's on the 10.12.1 Beta 2 but none have dual tbolt ports for me to test this..
 
How long typically after the Dev's beta's do the public beta's arrive?
 
Public Beta 3 is available.. I'm downloading now. Will report back.
 
So annoying!!! It has to be a display driver issue because I can plug my tbolt to Ethernet adapter into the other tbolt port and it works fine. If I unplug it and plug my monitor back in it doesn't come on.
 
I'm having this exact issue as well. I just got dual displays for the first time yesterday, so I can't say that they worked previously, but they don't work together now. I can get either to work on it's own, but not both to work at the same time. I'm running a mid 2015 rMBP AMD Radeon R9, with two ASUS VS248 displays, both HDMI > Thunderbolt. Sierra beta 10.12.1.

I tried using one HDMI > Thunderbolt and the other HDMI > HDMI, but no luck there either. Still only recognizes one.

I was on the phone with Apple for about 45min yesterday and they couldn't resolve the issue.
 
So you have the same laptop as the rest of us.. I'm wondering if it's an issue specific to this laptop. @drmito, what Mac do you have?
 
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