When an new item is received it is assigned a default bin if no default bin exists. However it is assigning the receiving bin and sometime the From-Production bin as the default for the item which it really should not as it is really not where it is stored.

I would recommend adding code to only assign the default bin if the bin is not the Receive or Ship bin or a dedicated bin. That way the default bin will be assigned to a pick able bin which is really where the parts should be stored by default.