[CBi]

I had this problem on both sides of my QP5, in my case on the rear stop lights that were causing an alarm on the dashboard... then it seemed everything was OK when checking back home.
Then one of the sides permanently stopped and I found that the issue was poor contact on the bulb holder, resulting in heat that had started melting the holder and internal casing !
I would recommend that you check all the bulb holders one by one = they are relatively easy to reach, a little less on the left side than on the right.