question

The 17.2 release includes this backwards compatibility note,

"Changed operators to not change their incline rotation when traveling on inclines."

The Truck flowitem is an Operator object and thus no longer rotates on inclines. The main benefit of the truck being an Operator is that it doesn't change Z height during offset travel (it won't climb into the air to pick up a box on the top shelf of a rack for example). If you're willing to trade this benefit for the previous incline behavior you can make the truck a generic Task Executer object instead.

You can run this script to turn the truck into a Task Executer:

treenode truck = node("MODEL:/Tools/FlowItemBin/Truck/Truck");

classes(truck).subnodes.clear();
treenode class = classes(truck).subnodes.add();
class.name = "TaskExecuter";
class.value = library().find("?TaskExecuter");

superclasses(truck).subnodes.clear();
treenode superclass = superclasses(truck).subnodes.add();
superclass.name = "Dispatcher";
superclass.value = library().find("?Dispatcher");

rebindobjectattributes(truck);