Admin won't load on fresh install when using Browsersync

I’m developing locally with MAMP Pro.

I just can’t get into admin when trying via localhost:3000 - just redirects to home.

Accessing via the MAMP server name, eg. mysite.dv/wp-admin - works fine. But localhost:3000/wp-admin will not work.

I have cleared all data, quit and relaunched browser and yarn.

Has anyone experienced or managed to solve this?