No issues with my UHD display on fizz Chromebox (cTL CBX1).
I'm currently at page  zoon 150% with expected  results.
If there is additional information that  would  help diagnose when this bug
shows  itself don't be afraid  to ask for more info.

@caitlin Are you sure you're running at 150 % on UHD?
I only have 100, 110, 120, 140, 160 … as available steps.


While trying this I have now set the HDMI UHD output to 120% – but from the Displayport output as the HDMI did not work afzer setting it to 140% scaling.

And now at 120% it seems to work. But when I go up to 140% again I do either get back to a fully black screen with just the mouse pointer or a frozen screen where nothing changes anymore.


Besides that I noticed that in extended desktop mode placing the HDMI output on the left side "catches" the mouse pointer that screen: You cannot move it back to the Displayport screen on the right. I need to unplug HDMI so the mouse jumps back to the then single screen on DP.

But when I place the HDMI screen on the right side moving the mouse pointer between the two display is no issue.


Overall this seems like some really hidden driver issue here that causes quite same erratic behavior in several ways.

I've verified under a different account that it's broken at 140%.

But under both accounts not just 120 % but also 160% work correctly.

140% scale works fine again after updating to 69.0.3497.14  :-)

Thanks for fixing!