@Cathal Geoghegan Thanks for your patience on this.
I have summarized our offline discussion and sharing the below answer for the benefit of community.
Suggested customer to create a new user in Active directory and assign contributor role on subscription and requested them to login to Visual studio with the new user.
Post the login they are able to create the publish profile and able to publish their solution to Azure webapp without any issues.
Feel free to reach back to me if you have any questions on this.
Please accept as Yes if the answer provided is useful, so that you can help others in the community looking for remediation for similar issues.