It seems like a bug to me, because the variables don't work in the file path field of a Set Card Variables action, but they do work in the folder path field.
The dispatch script has a user-defined variable called Package File, which contains the name of a file other than the one on which the script is being run. The setup of the Set Card Variables action is shown below.
When it runs, I get an error message that says "Error, file %Package File% doesn't exist". BUT if I select "Folder with path" and put the same variable in, I get an error message that says "Error, folder R07F95_Software.zip doesn't exist", because, obviously, it's a file not a folder. But it correctly expands the variable. I've also verified the value of the variable with a message box. I've tried it with other variables, and the built-in ones work, but none of my user-defined variables work as a file path.
Can anyone reproduce this problem? Is there something I'm missing? We recently upgraded to 2016, but I never tried this specific thing in earlier versions.