Laravel 5 - Cannot get authenticated user from subdomain despite setting universal session domain

I have 2 Laravel projects (one is 5.4, the other is 5.7) installed on the same server, currently dev'ing via Valet in my local environment.

What I'm doing now is trying to direct users from example.app to booking.example.app as the Booking site requires an app for itself.

However, after logging in example.app, opening booking.example.app would show me I'm not authenticated (i.e. dd(Auth::check()) returns null). I have done sub-domain cookie/session sharing before and never came across this before.

Both app has the following configurations:

example.app

SESSION_DOMAIN=.example.app

SESSION_DRIVER=cookie

SESSION_COOKIE=example_session

booking.example.app

SESSION_DOMAIN=booking.example.app

SESSION_DRIVER=cookie

SESSION_COOKIE=example_session

What am I missing here?

via Chebli Mohamed