AS400 Trucking, TMS and Logistics Software

Is AS400 trucking and dispatch software still supported and actively developed?

Yes, for the established transportation technology vendors serving this niche. Dispatch, fleet maintenance, and multi-carrier shipping products with IBM i roots are current, actively developed products, several from vendors who also sell cloud versions of the same capability. Confirm with any specific vendor whether the version you are evaluating is their actively maintained release, since some products in this space have gone through multiple acquisitions.