This sounds like an issue that was addressed in a maintenance release of Tableau Desktop. From our release notes page for 9.1.3:
"In Tableau Desktop, when you connected to a SAS statistical file, the number of rows read from the file were sometimes truncated without any indication."
- If you are not already on the latest build of Tableau Desktop (currently 9.2.5), I would suggest upgrading and testing the file again.
- If you are already using the latest Tableau Desktop, I would suggest opening a support case either through your customer portal, or through the web form, and supplying our support team with the .sas file encountering the issue. If they can reproduce the issue in-house they should be able to help.
I hope this helps!