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M1 MacBooks: Continued Display Issues After 11.1 Update and Compare with 16" MacBook Pro

9:42 video

Apple released macOS Big Sur 11.1 this week. Did it resolve my persistent external display issues on my M1 MacBooks? No.

A few weeks ago, I posted about performance and display issues with my M1 MacBook Air and Pro, and a follow-up explaining that some performance issues were due to the codec I used for editing or unoptimized apps under Rosetta. What kept bugging me were the slow USB-C speed and my external monitor only displaying 30 Hz through Thunderbolt and DisplayPort. After the 11.1 update, they can now display 60 Hz with my BenQ PD3220U.

What 11.1 didn’t fix

  • USB-C speed: no improvement on my T7 SSD; the M1 MacBooks are still much slower reading it than my Intel Mac.
  • New display issues. After lunch, waking the M1 MacBook Pro connected to the BenQ via Thunderbolt produced a weird scaled-down version of the 4K display, with part of the built-in display mirrored on the BenQ and distortion and ghosting. Display preferences show the correct configuration (the MacBook display to the right of the BenQ, running at 60 Hz). Disconnecting and reconnecting the Thunderbolt cable fixes it, but it happens frequently when the computer sleeps and wakes. It happens on all three connection options with the BenQ and the MacBook Pro M1.

Tests

I tested the MacBook Pro M1, MacBook Air M1 and 16-inch MacBook Pro with the BenQ over HDMI, DisplayPort and Thunderbolt:

  • Thunderbolt direct to the monitor: the Pro M1 distorts on wake. The Air didn’t show issues. The 16-inch looked fine at first, but later the external display wouldn’t turn off and kept cycling on and off, as if looking for a new source; it also had a state with 60 Hz but limited resolution options (a disconnect and reconnect restored resolutions, but then I couldn’t get 60 Hz).
  • HDMI via Apple’s AV adapter: the Pro M1 had the same distortion. The Air woke with colors inverted or discolored (fixed by disconnecting and reconnecting, until the next sleep-wake cycle). The 16-inch worked just fine.
  • DisplayPort through a CalDigit SOHO dock: the Pro M1 had the same distortions and duplicated part of the display; the Air and 16-inch seemed fine.

I became fairly confident the BenQ was the problem (a shame, because it’s amazing). Before returning it, I tested a basic Samsung UJ59 32-inch (under $300): no wake issues over DisplayPort or HDMI with any of the three MacBooks. But I don’t want to use it daily: the angles aren’t great and HDMI won’t go over 30 Hz at 4K (DisplayPort gives 60 Hz). At Best Buy, the only in-stock 4K monitor was the 28-inch Samsung UR55, which I tested: with DisplayPort, all three computers seemed fine; over HDMI, all three constantly cycled on and off as if searching for a source, like the 16-inch did on the first monitor.

I tried different cables and adapters, DisplayPort on two docks, HDMI on a dock and the Apple AV adapter, different Thunderbolt, HDMI and DisplayPort cables and different monitors, and all three computers were updated to 11.1. A last test with a Dell PC found zero issues over DisplayPort or HDMI to any of the displays.

Conclusions

  • My issues continue, or evolve: 11.1 fixed the refresh rate problem, but I now have additional issues waking external displays.
  • Distortion, discoloration and source-searching aren’t 100% guaranteed but happen often enough to be expected. Each computer and monitor combination had its own unique issues.
  • DisplayPort was a bit more reliable than HDMI. The cheaper UJ59 worked pretty well.
  • The 16-inch MacBook Pro was the most reliable, best on DisplayPort with the Samsung monitors. The M1 Pro had the most issues, and the M1 Air was the only one reliable over Thunderbolt directly to the BenQ.

It seems absurd, and I never thought I’d need to choose a monitor on compatibility rather than connections. I don’t think it matters whether the cause is the MacBooks or macOS: I saw no issues with a Windows PC, which cuts down on variables. It needs to be fixed quickly “before I pull the rest of my hair out.” Until then, I can’t take lunch breaks that let the computer sleep. If you have suggestions, let me know (as long as they don’t involve buying more monitors).

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