During the final stage of the ASN when you're assigning locations to each sku you have to press the Assign button to lock the locations into place. However sometimes the team forget to do that and go straight to Book In ASN (ignore the pop up as most people do plus it pops up when you've done it correctly) and as a result all the stock is booked in against unassigned locations meaning you then have to do all the admin to transfer stock around.
We already have Allow Unassigned Locations toggled off on our warehouse settings so something isn't working as it should.
I ticked 'do not allow unassigned locations' on the warehouse - problem solved!