To be honest, I don’t even know how to approach this problem. I also saw this, I see how LockScreen can appear in different ways (sometimes some functions are not called). so I don’t know yet.
maybe this is due to the transition from AOD to lockscreen, and something happens there later.
Disabling both Pick up and Pocket from Ambient display seems to have fixed this for me. I'll test if it reappears if I enable Pick up gesture.