Hi @mahder,
Welcome to the Auth0 Community!
You should not use a post reg action to update user metadata. Please see this FAQ for more details: Can I use a post-user registration action (or hook) to update a user?
You should be able to accomplish what you have described with a post-login action here. Let’s take a look at how you’ve set up your action.
Can you please DM me the name of the effected tenant so I can take a look?