Aero peek not working and multiple thumbnails not showing up

I think this happened after I've set visual effects to "adjust for best performance" and set it back to custom and enabled all settings later on. Here are screenshots of settings i currently have set:


Desktop peek is working fine, but when I hover over window thumbnail, it doesn't show me the window.

Also if I have more than one windows from the same program opened, it doesn't show individual thumbnails:


Any idea what could be causing this?

Fixed it by going to regedit and setting DisablePreviewWindow to 0 under Advanced and setting NumThumbnails under Taskband to higher value, both of the folders were in HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer