SQL Server can't see subst/virtual drive I have been having trouble getting SQL Server to see subst/virtual drives at all. 

For example:
I've used the subst command to create a F:/ drive that maps to C:/FDrive. The stored procedures use this F:/ drive to generate various files. If I programmatically change the folder location within the stored procs from F:/ to C:/FDrive they execute successfully. 

Is there a fix or workaround available?
It's because subst just gives you a drive letter alias for your current session; it's not a server level thing.  This is not going to be possible using this command.  Use the real path instead.