Mercedes CLA C117 (2017 ed) left indicator turns on both front turn signal lights

Hi guys,

I recently replaced the driver-side (right) headlight on my CLA C117 220d (2017 ed) with non-OEM headlights, including a new control module. Now when I hit the right indicator, the right front indicator light doesn’t turn on. However, when I press the left indicator, both of the front indicator lights turn on.

Aside from this, the headlight works well. The daytime running lights work, as well as the normal lights and the highbeams. I presume there might be some ECU / Coding / Wiring thing going on.

Has anyone come across this before? How can I diagnose what is going on (without going to the Mercedes dealership), and what can I do to fix it?