Dear All,

 we are now using office 365 pro plus. we are facing some days excel file issue. when i open multiple excel file & minimize on taskbar. showing excel file thumbles  hidden on taskbar. 

  Already trubleshoot below step

  1) repair office 365 

  2) reinstall office 365

  3) format system install fresh operating system & fresh install office 365

  but issue is till not resolve excel file issue. please give proper solution