If your Office 365 Excel spreadsheet is not syncing correctly, or recently added columns are not appearing in your app, re-adding the spreadsheet connection can refresh the data source.
This process should pull in the latest spreadsheet structure without affecting the existing data in your app.
Reconnect the Excel Spreadsheet
Open the Data Editor in your app.
Click the plus sign (+) to add a data source.
Select Excel.
Open the dropdown displaying your Microsoft email address.
Select Add Microsoft Account.
Complete the Microsoft sign-in process.
In the Select a Library window, locate the same Excel file that is currently connected to the app.
Click Choose Library.
The spreadsheet will be re-synced with the app, and any recently added columns should now appear in the Data Editor.