I have a EU Zforce 950 Sport, with trailer plug installed (factory).
The know issue is that trailer has working position lights, brake lights, plate lights and BLINKER NOT WORKING IN THE TRAILER, but yes in vehicle.
The issue is a missing part. Exactly this part, that is connected near to acelerator pedal (you will see a black free conector)
7030-160602 Trailer Turn Light Control Unit (description is very concise)
You need to add this part (of course, the other wiring parts), if you don´t, your trailer turn indicators never will work.
Regards