AaronTRoach apologies for the delayed response, I don't have notifications turned on for this post.
I'm not sure if you managed to unblock yourself, but my thoughts would be to ensure that the user was fully purged from the SWA platform (https://docs.microsoft.com/en-gb/azure/static-web-apps/authentication-authorization?tabs=function#remove-personal-identifying-information) as there may be something in cache that was meaning that the updated claim field was not being respected.
Also, somewhat related to your original question, a new preview feature was released that allows you to call a custom function once the user has signed in (Public preview: Customize Azure Static Web Apps authentication with a serverless function | Azure updates | Microsoft Azure). Presently, that's only for applying custom roles, but you could abuse it to add more profile information. Hopefully this does represent the first step to getting the ability to create a larger profile for a user (but that's more me speculating than anything).