Hi Jessica,
Welcome to Microsoft Community.
Based on the description, what happened on your side is actually a default behavior, see this official reference: Microsoft Forms and Excel workbooks - Excel.
Generally, if a form is created from Forms on the Web, then we can only get workbook each time via clicking the 'Open in Excel' button and can NOT sync with new responses. While forms created in OneDrive or Excel for the Web will be able to sync latest updates in that workbook.
The reason is mainly because if you want to use the sync feature, it has to be connected with some cloud storage service to save the workbook. Hence, forms created in OneDrive or Excel for the web will make a workbook connected with the form and save it in your OneDrive storage place and update the data in there automatically.
Hope this can help you understand the way how synced workbooks work with forms and make your work more efficiently next time you use Forms.
Have a nice day and take care.
Best Regards,
Mia