//EDIT: for clarification read comments!
T1 trucks are loading goods according to the option I marked ("allow partially loaded trucks" NOT checked). However, I recently introduced T2 trucks by advancing in the game and T2 trucks are not respecting the setting. So far I have only seen them do so with fluids, but I feel like this is a bug...
In the picture you can see a T2 truck just loaded sewage from a tank. there was enough fluid available to fill the truck. however, the truck is driving away with only 1/3 of it's cargo hold (i.e. 20). The destination is a dumping outlet, which was empty at the time the truck was loading.
This is happening consistently. I have never seen a truck take a full inventory of sewage on that route (fluid storage to dumping outlet). sometimes it's 40 and sometimes it's 20 fluid. I have not had the chance to look at the T2 truck taking other hauling jobs as the two I have have been focusing on the sewage exclusively. I will report back.
The save at the moment of the picture is provided.

