It seems like I can only stop one person then when I complete the traffic stop and move to another person the shift button will no longer tag a new person for a new traffic stop. Here is a list of other mods that I also use: Traffic policer, Arrest Manager, Assorted Callouts, LSPDFR+, Police Smartradio. Is it like some thing that I'm forgetting to hit to end a traffic stop or what?

Not sure restart pc maybe, or reset game. Or update lspdfr

hmmm sure but this happens every-time I try to play the game and all of the mods are up to date. Am I seriously stuck with restarting the game every-time I complete a traffic stop?

Are you sending them on their way or just leaving the scene while they sit there?