Headlights not working properly?

That sounds like the DRL relay has failed or isn't switching properly. It is in the relay box on the radiator support. When it is in the off position it loops the grounds so that the bulbs get effectively half the voltage they need. Then when you switch the lights on the relay moves to on and now you have full power high and low lamps. It is a 4 pin relay with 2 large terminals and 2 smaller ones. To test if it's the relay you could unplug it from the socket then take a piece of wire and on the connector side bridge across the two larger terminals (2 in blue). Try the lights, if they now work on both beams the relay either isn't being controlled or it has failed internally. A test to see if it's the control circuit would be to connect a test light to the two smaller terminals in the connector (orange). Turn the lights on and the light should turn on if the control voltage is working. If the relay is plugged in you can also have someone turn the lights on and off and see if you feel it click. Then try the jumper wire, if the lights now work, replace the relay.
If they are still not working then the next step is to go to the DRL controller behind the dash over the glove box. That is a dealer part though so hopefully the jumper makes it work so you can replace only the relay.
There is also a way to disable the drls and make the system a standard system, that is covered in the TSB- Electrical EL011-00 If you search that TSB it covers the process.

Shouldn't be a problem as it basically just adds the ground. Not sure what it does with the DRLs though.

Yeah, it is that. I don't see where it would cause an issue other than the DRLs not working, which if the wiring is correct shouldn't be something that would set a code. You may want to make the wire heavier just to keep the current draw happy but that's about it.

Good to have options. Thank you for using 2CarPros.