Both ambulances have irregularities with the lights. Sometimes they work, sometimes they don't, and they are really really dim which makes them impossible to see during the day.
I also took a small video from this, you pretty much don`t have any more blue lights and the lights bar on your vehicle kinda gets messed up, we tryed putting the vehicle in garage and then pulling it out again, pulled out a different ambulance we still had the same issue. What seemed to resolved the issue was to relog.