Mac Studio external displays freeze after waking from sleep on macOS Tahoe

Summary: External display freezes after waking from sleep on macOS Tahoe — matching refresh rates appears to fix it. I'm still looking for a reliable way to configure distinct refresh rates. Not sure if it's related, but I found a similar issue in a community post: macOS Tahoe not waking Extended Display - Apple Community

I’ve been troubleshooting an issue on my 2023 Mac Studio (M2 Max, 32 GB RAM) running macOS Tahoe 26.6.2 where the displays would frequently freeze after waking from sleep.

My setup is:

• Main display: LG UltraWide, 3440×1440, connected via USB-C through an OWC Thunderbolt Hub
• Secondary display: ASUS VG279QM, 1920×1080, connected directly to the Mac Studio via HDMI
  • The secondary display is rotated 90 degrees and used as an extended desktop

The issue occurred consistently — roughly 80% of wake attempts, especially after the Mac had been asleep for a longer period.

Interestingly, the Mac itself did not seem to be fully frozen. Keyboard input still worked. For example, I could type the correct password even while the screen was visually frozen, put the Mac back to sleep, and then wake it again. On the second wake, the lock screen would sometimes render normally. I also tested the setup with the HDMI cable for the secondary display disconnected, and the problem did not reproduce. That made me suspect the multi-display configuration or display reinitialization during wake.

As a troubleshooting step, I changed both displays to the same refresh rate. First, I set both displays to 60 Hz. Since making that change, the wake-from-sleep freeze has not occurred at all over several days of use. I also tested setting both displays to 100 Hz, and the issue still did not reproduce. Before this change, the two displays were running at different refresh rates. So at this point, my working theory is that the problem may be related to mixed refresh rates across multiple external displays during sleep/wake, rather than 60 Hz specifically. This is only based on my own setup, so I can’t say for certain that matching refresh rates is the actual root cause.

If anyone else is seeing a similar issue with multiple external displays on macOS Tahoe, it may be worth testing whether setting all displays to the same refresh rate changes the behavior. More importantly, please let me know if you have found a reliable way to configure multiple external displays with distinct refresh rates. This would be a great help, since one of my extended screens is used for gaming.