Welcome to our forums! I’d be glad to help investigate this issue you are seeing with the UGA-HDMI-S. Generally it is best practice to directly connect our UGA-HDMI-S directly to your computer, as introducing new variables like a USB extender can potentially cause issues.
In theory it should work although the longer the distance a video signal travels in such as a longer cable, the weaker its signal integrity is. It may be possible an “active” usb extension cable could provide more consistent results although results may vary.
If I may ask, if both UGA-HDMI-S are directly connected to your computer is the video signal stable? If this issue is more so isolated to whenever the USB extender is connected to your computer then, that is likely the cause of this issue.
Please let me know if you are able to do some of the follow up testing or if you have any questions we are here to assist.
Thanks,
Alberto
Plugable Support Specialist
Plugable Technogies