I seem to have found a bug in Sigmastudio 3.17.
It's not compatible with any of the previous versions.
I can load a file created by 3.13 into 3.17, but if I output a file from 3.17 then I can't read it into 3.13 without an error.
Specifically, the output cell assignments don't show up and I get an error when trying to compile.
This is a real dis-incentive to upgrading since many people share the files and maybe not everyone upgrades SW at the same time.