I think the crew leader field on the work ticket is set to be the crew leader of the route it was most recently placed on via the schedule board. I’m not sure how your schedule board is set up, but if you click into a route name on the board, or go to “manage routes” in the top right three dots, you might have a route or routes which are assigned to the ex-employees. You can edit that on a route-by-route basis.

We sometimes have this issue with our truckers - crew leader A is the guy doing the job, and trucker B is the guy who at the end of the job, maybe the next day goes and picks up the equipment and brings it back to the shop. Even though it would make sense for A to be the crew leader, since B is the last person to have it on their schedule, the ticket’s crew leader gets set to B, because he’s the last guy to have it scheduled on.