Sql proxy account not working when user logged off

Hi 

I have a SSIS package that executes a gpg program via command line.  The SSIS package runs from a SQL Agent job using a proxy account (a domain account).  This account has an administrator on the server so should have full access to run the gpg program.

These are expected: 
- The SSIS package runs when executed manually.
- The SQL Job runs when executed manually.

Here is where it is unusual:
-When running automatically when scheduled, the package executes successfully only if the proxy account (a domain user) is logged into the server.
-When the proxy account is logged off, the scheduled job fails when trying to execute the GPG command line program.

Any ideas?


Thanks in advance for any advice!

I have done so much research and it appears the proxy is setup correctly in SQL Server.