We definitely recognize the popularity of this feature, and we discuss it constantly during the planning phases. However there are certain technical limitations in the system that add a large amount of development cost. Because of the cost and the fact that there is a workaround available, other features get prioritized over this one.
That being said, please keep voting for it. The popularity of the feature does help bring it up and makes us reconsider every time.
Apologies for the delay.
We’re doing some research both on the specifics of this ask as well as what it would take to support this.
Is the ask here to do the same thing that regular Azure AD does (see: https://blogs.technet.microsoft.com/enterprisemobility/2014/12/18/azure-active-directory-now-with-group-claims-and-application-roles/) or is are there different requirements around this for Azure AD B2C?Marcel Juhnke commented
While this is still not available natively, you can get around this with a custom policy and using RESTful API integration. You will need a service that is called by the User Journey which in turn queries the actual Azure AD behind the B2C tenant for the user's group memberships.
If anyone is interested, we have written a small service to do exactly that as we faced the same issue: