I faced a similar issue today , and it turned out that the error was not related to access permissions but rather to the file format itself. Ensure that the details in your upload file are in the correct format and not corrupted in any way. Sometimes, errors can occur if there are unexpected changes in the file structure, such as merged rows or columns. Double-checking the file format and structure could help resolve the above issue.
Hi @Jane McCusker , welcome to the Atlassian Community!
It appears that other users of that app had that issue in the past, see their support forum:
And they were asked to raise a support ticket.
As a result, I would recommend contacting their support team for further assistance (they're currently open it seems).
Hope this helps.