Google map in Flutter not responding to touch events

I was with the same problem and I found the following solution after a long time of searching, just so it will work:

GoogleMap(
   gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>[
      new Factory<OneSequenceGestureRecognizer>(() => new EagerGestureRecognizer(),),
   ].toSet(),)

The reason is that the EagerGestureRecognizer is a gesture recognizer that eagerly claims victory in all gesture arenas.

Reference:

Manage gestures priority between two widgets

propriedade gestureRecognizers