Hi everyone :)
yesterday I received my PA32QCV and overall I'm very happy with it. Great panel, no great backlight bleeding, no dead pixels. However, I've run into a reproducible issue with the Thunderbolt 4 input and check if others are experiencing the same.
Setup:
- MacBook Pro M4 connected via Thunderbolt 4 to the TB input port on the MacBook.
- Mac mini M1 connected via USB-C to DisplayPort 1.4
- Monitor firmware: MCM102 (latest)
The problem:
Whenever the monitor is fully powered off using the physical power button and then powered back on, the Thunderbolt 4 connection to the MacBook is no longer established. The MacBook does not detect the monitor at all, no display signal, no USB hub, no power delivery.
Re-plugging the Thunderbolt cable on either end does not help. macOS does not show any connection prompt or error. The DisplayPort connection to the Mac mini, by contrast, works perfectly after every power cycle.
The only workaround that restores Thunderbolt functionality is to fully disconnect the monitor from power, wait for the capacitors to discharge, and then power it back on. After this cold boot, Thunderbolt works again, until the next time the power button is used to turn the monitor off.
This behavior suggests that the Thunderbolt controller inside the monitor does not properly reset its internal state during a soft power cycle (power button off/on). After a soft power-off, the TB4 controller appears to remain in an undefined or hung state, preventing it from completing the Thunderbolt link training handshake when the monitor is turned back on. A full mains power cycle forces a complete hardware reset of the controller, which is why it resolves the issue.
I think this is not a macOS issue or a cable issue, the symptom is entirely on the monitor side. The MacBook's Thunderbolt port and the cable work correctly in all other scenarios.
What I've already tried:
- Re-plugging the Thunderbolt cable multiple times after power-on
- Waiting several minutes before re-plugging
- Changing macOS accessory security setting to "Always Allow"
Is anyone else experiencing this? And is ASUS aware of this issue? A firmware fix that properly reinitializes the Thunderbolt controller during a soft power cycle would resolve this completely. I'd like to avoid a unit exchange if possible since my panel is otherwise excellent, but this is a clear functional defect.
Thanks in advance.