I have a Framework 13 with an AMD 7640U connected to an LG 34BK95U-W monitor via Thunderbolt. It dual-boots Ubuntu 22.04.4 LTS and Windows 11, and I only experience this issue in Ubuntu.
When I first connected the laptop, it picked the wrong resolution, but that was easily correctable. After that it worked great for a while.
Later on I came back and woke it up from sleep, and that’s when the problem started: lots of flickering and portions of the screen sometimes staying white. It seems to be dependent on what’s under the mouse, with little or no flickering when it was over the desktop, but issues anywhere else: left side bar, applications menu, firefox, settings app, etc.
It’s a little hard to describe, so I also took a video: https://youtu.be/woOP5RJKM_k
I tried disconnecting and reconnecting the thunderbolt cable, which did not help. Then I rebooted the laptop, which fixed it until the next time I woke it from sleep.
I normally use this monitor with a macbook and it works fine there (although I did have to do a firmware update to the monitor to fix an issue that cropped up after a macos update.) I have also used it with windows on my FW13 and never had any issues, so I believe this is a software bug rather than a hardware issue.
(Note: the 34BK95U-W is the business version of the 34WK95U-W; I believe the hardware is identical and the only difference is that the business version had a better warranty.)
Updates:
- I tried rebooting the monitor (by unplugging it from wall power and then plugging it back in), and that fixed it once, but not a second time.
- I tried forcing the DisplayPort version to 1.2 instead of 1.4, but that didn’t fix it.
- I opened up the laptop (I had been using it in clamshell mode) and noticed it’s screen was exhibiting the same issue, and that the issue remained even after disconnecting the thunderbolt monitor!
One more update: today, my laptop went to sleep after rebooting, but before I opened anything, and when it woke from sleep, the display was fine. So maybe it’s a combination of waking with the TB display + firefox opened?