As I know, it is due to permission propagation to take a couple of minutes effective in some cases
- when we add a user to a existing group, share dashboard to that group, the dashboard shows up for him after 5min
- share dashboard to a existing group, add user to that group, the dashboard shows up for him after 5min
- delete user in group, after 5min, the shared dashboard hides for him after 5min
So I also deployed a lambda that is hooked onto the CreateUser CloudTrail event from EventBridge to grant assets access to users directly. It takes effective immediately for users first logging.