My Carpenter was walking around in the City to gather mats for his next order.
His Backpack was empty all the time.
Back as his Toolbench he put everything out, which he needed but which was not in his empty Backpack.
Here is a screenshot before he put out the stuff on the bench:
As you can see his Backpack is empty.
Here is the save file, from the same time:
Version Number and Mods in use:
A20 r701 x64
Yang & co’s Armoury
Hearthlings of Many Faces
Slabs with terrain colors
Settlement Decor Mod