"Check Side Lights" error, but all bulbs are working

[TowX]

Started yesterday. Whenever I turn on either the parking lights or the headlights, the error pops up. But all the bulbs front and rear are working fine.

This may sound nuts, but are the lights on the fenders (behind the front wheels) supposed to light up with the marker lights or just the blinkers? I never paid attention before. But mine only flash with the blinkers, do not light up with the markers. Could that be it?

If not, what other electrical gremlin has my X5 been afflicted with this month?