I had same experience under warranty: “Check Low beam” message came on; Dealer fixed it and reported “changed bulb and ballast”; Bumper came out slightly two weeks later and dealer did not want to admit that it was related to the bulb change.

One year later I took the bumper off and discovered that tabs are missing/Brocken on the $20 part. Installed replacement part and bumper sits perfectly now.

Occasionally my left low beam would not turn on now. It was “muddy” for about a month and now it does not turn on at all. I checked that left assembly did work on the right side.
Unplugged LCM and plugged it back and both lights worked. Start driving and left light stop working again. Unplugged LCM again end everything worked for a short while.
It looks like LCM detects some fault and shuts the power to the light. I will try to install new bulb on the left side and swap left and right ballast and igniter.
I will be able to detect that problem was with the bulb if light works; problem with LCM if left light will not work stably or problem with ballast /igniter if right side will have an issue.
Anyone knows warranty for LCM. Warranty booklet states 7 years and 70000 miles for various control modules. Does it include LCM?