Hi @DonV ,
Could you please share more details about the error message on your side?
Based on the issue that you mentioned, I have made a test on my side, and don't have the issue that you mentioned. According to the OneDrive shared link that you provided, I found that the data within the Excel file has not be formatted as a Table:

Please consider format the data in your Excel file (OneDrive shared link) as a Table, then re-import data into your CDS Entity, then check if the issue is solved.
Note: When importing data from a Excel file into a CDS Entity, please make sure the data in this Excel file has been formatted as a Table alreadly.
More details about formatting Excel data as a Table, please check the following article:
https://docs.microsoft.com/en-us/powerapps/maker/canvas-apps/how-to-excel-tips
More details about importing data from Excel into CDS Entity, please refer to the following article:
https://docs.microsoft.com/en-us/powerapps/maker/common-data-service/data-platform-import-export
In addition, you could also consider take a try with the "Edit data in Excel" functionality in CDS Entity and the "Dataflow" functionality in PowerApps to import data from a Excel file into your CDS Entity, then check if the issue is fixed.
"Edit data in Excel" function in CDS Entity
Dataflow" functionality in PowerApps
Best regards,