Cannot get session to work in iframe on iOS Safari

I have an iframe on Site A with src set to a subdomain on Site B (both https). On Safari the session is not being retained in the iframe. I believe this to be related to first/third party cookies, so I have ensured that the session cookies and any other cookies set have SameSite=None and Secure specified.

I have attempted to integrate the Javascript Storage API, but hasStorageAccess always indicates that the client has storage access, so never calls requestStorageAccess. If I remove the hasStorageAccess check, requestStorageAccess always fails and never asks the user for permission to allow storage.

There are no problems on desktop browsers or Chrome Android, this only occurs on iOS (multiple iOS devices tested). Can anyone please suggest anything else I need to do?

I have the same problem, did you ever get this to work?

Cannot get session to work in iframe on iOS Safari
 
 
Q