Excel leaves task in background processes Excel.exe /restore

I have several excel reports that run as scheduled tasks to email reports.   All exit paths that I have found include an Application.Quit.    As scheduled tasks, these reports run as a Background Process.  

When they run, they include the entire activation string as the command line.  

 program files (x86)\...\Excel.exe /r filename.xlsm /p /argumentstring

But, sometimes a Background Process is created that shows in taskmgr in the command line

EXCEL.EXE /restore.   

This task never ends and has to be killed manually in Taskmgr.   Over the course of a week, a significant number of orphan processes collect.

I have searched and searched for a /restore option for Excel.   The closest was  /r for readonly.

Does anyone have an idea what the /restore argument is for this Excel process and what could cause it to be created?   If Iknew what