On the top right is my housing centre. It is not a District.
On the bottom right and stretching up to centre-right is my first research/production centre. It is not a District.
Across the top is three new production/research centres. They are not Districts.
The only thing connecting them is the train and so it can’t be over-ridden by cars/trucks. There is enough production of the demanded items. There is nothing being delivered to the trains station (Station is empty).
The trains are not running.
I seem to have connected them all correctly with the correct roads in the right places, they all have power and still nothing.
I’ve set up districts with export rules.
I’ve uninstalled and reinstalled and started a new game.
And still no trains.