Same problem. Save game to see it in action.
Drones drive from the requester depot to the supply depot, take the resources, sit for a time then vanish, the resources are deposited into the requester depot and the drone again drives to the supply depot to "take" more.
Factorio version: 0.18.36
Mods:
Krastorio2 v0.9.23
Transport Drones v0.7.8
(and other QoL addons)
OneDrive link to my latest save file: https://1drv.ms/u/s!AvSvmoB97irMgtF9hK7zfxV-rrQ0ww