Hovering over a window won't peek when another window is open - Microsoft Community

so when hover on window in task bar little thumbnail pop , once hover on "preview" of sorts similar when use aero peek desktop feature, window visible , no longer happening , find annoyance when trying multi task 

edit: being mean hard put words when hover on spotify thumbnail doesn't display preview, hope clarifies meant

this not feature disabled. if not using tweaking program of sort

should have make change in registry disable peek.

you can verify if peek has been disabled in registry looking key in article below.

- if have extendeduihovertime registry key described in article below, change value 1000

( default 1sec. hover time before thumbnail pops ), or less, 500,  if prefer.

or. key not default on win10, delete the  extendeduihovertime  key.

http://www.windowscentral.com/how-disable-taskbar-thumbnail-preview-windows-10

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Windows / Windows 10 / Desktop, Start, & personalization / PC