I've been using this thunderbolt dock for the last 6 months, no problem. I've got it plugged in to my laptop, using the laptop's screen as the main screen. For some reason, the signal became unstable (would randomly black-screen for a couple seconds every once in a while - one or the other or both external monitors) after about 6 months and I had to drop down to 1 external monitor until I got a new one to replace it. I've replaced it with the same dock again and I'm back up to 2 external monitors with no stability issues. Now that I've replaced it the signal is stable again.
However, now I'm having another issue that I never had with the old dock. When I lock my computer, if I unlock it right away everything is fine and works perfectly. If I lock it and leave it for about 15 seconds, the laptop screen (main screen) goes dark - fine. But when I come back and move the mouse or hit a key to wake it back up my monitors just freak out. Going back and forth, resizing the main monitor, takes forever to get to the point where the login on the lock screen is responsive. And then sometimes (when I hit a key instead of moving the mouse and waiting) all of my windows will go back to the laptop screen (main display). There was a recent Windows 10 update, but I performed that after these issues first appeared.
Is there something wrong with the dock, or how Windows is handling it? I've got a Samsung S27A600UUN and a ViewSonic VA2719-2K-SMHD connected to the dock with HDMI.
As a workaround, I thought making it so the lock screen stays up when locked would be the easiest solution. I've to changed the Sleep/System unattended sleep timeout advanced setting to 0 minutes and the Display/Console lock display off timeout to 0 minutes, but the behavior still exists. Are there other settings that might work for this?