yeah i got the same issue, my chicken restaurant staff is not picking up the cargo

I have the same but with the casino

I had this issue, where my truck was stuck in loop between a shop and factory and never unloaded. It turned out that there were products in the van that the premises couldn't accept. To get around this, I cancelled the delivery route, sent the van to the university (or scrapyard/gunshop as they will accept any product) once it had been fully unloaded and was on it's way back to the factory I ensured that only the products for the shop were selected in the delivery van (e.g. meth products for a chicken shop) then I set up the delivery route again and it unloaded as normal. I think as when you buy a vehicle the default setting is that the vehicle will accept all products, the workers can quickly place other items in the van and it causes this issue.

Alternatively, (and if you don't care about losing product) you can just go in build mode, select move, pick up the garage in question and place it back down where it was (this removes the products inside) make sure you only have products suitable for destination shop ticked on the vehicle/garage and this should fix the vehicle not delivering too.