In a recent beta the batch switching would say All Stores are not buying from the same supplier and wouldn't even let you switch the ones that are. I didn't like the fact that it didn't allow me to batch switch any of the stores, however, I really liked the fact that it told/reaffirmed the rules for using batch switching.
In the latest beta that messaging is gone and it just batch switch for the stores it can. So naturally I would like to see a compromise implemented where if all your stores are not buying from the same supplier it batch switch the firms it can and then text underneath the result tells you that X number of stores and purchasing units wasn't updated because they did not buy from specified supplier.
OR EVEN BETTER
It gives you the option to batch switch the remaining firms anyway....but this could be an issue if you place your company products are floor 1 and on floor two you carry your competitors products (an idea I plan on trying out)