Postgame won't trigger (Spoilers)

So I«ve beaten the E4 and I’ve read that someone calls you over to the lab. But I’ve wondered around the region for an hour now and no one called me yet. Is this a bug?

Go to Suntouched City subway. It’s in the bottom right of the city.

I’ve tried that a few times, the train guy is still there and says the station is not open to the public

Go to amphrite city cave and defeat the timeless first then.