Windows 10 Taskbar preview stopped working

I've got a new GPU today and suddenly the taskbar previews stopped working. Here is how it looks like now:

However it still works fine if I only have 1 window opened. If the same program has 2 or more windows open the preview doesn't work and shows up as on the first screenshot.

Here is the proof that it works fine with only 1 window opened.

Is there any way to fix it? It's not just for steam. If I open multiple explorer windows the preview stops working but with only 1 window it works fine.

The OS is Win10. The new GPU I've got is GTX 1080 if that's of any difference On my old 970 the preview used to work fine even with multiple windows open.

Solution 1:

It's possible that the NumThumbnails registry value is set to 1. What it does is if you open more than one instance of the program, it stacks the items instead of showing the thumb images.

Start Regedit.exe and go to the following registry key:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Taskband

Delete the NumThumbnails value

Exit Regedit.exe, logoff and login back.

(via Increase Taskbar Thumbnail Preview Size in Windows 7, 8 and 10)