I had issues trying to run powershell from sql agent but got the following to work:

(1) use the SqlCmd in the step.

(2) created a batch file that containted the following:

REM change to the correct drive

I:

REM change to my working directory

cd \mydir

REM now call powershell script

C:\WINDOWS\SysWOW64\windowspowershell\v1.0\powershell.exe -Nologo -NoProfile -Noninteractive -Command "& 'I:\DataXfer\ssh\myscript.ps1'"

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NOTE: the string following the -Command

you must have a "& '\pathname_script' "

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