Hi @SMassey10,
I just tested your xlsx file publishing from 3.12 release and 3.13 beta Connect, and when I open in either 3.12 or 3.13 beta I do not see that error.
When you check the version locking in the setting for the survey in the website, what version is currently being used when the survey is opened in the web app?
If it happens again, can you confirm what browser they are using, the version of the browser, and also on what OS version.
Regards,
Phil.