When placing droppers and dispensers, the parts that drop items, place blocks, and spawn entities will always face south unless placing a dropper or dispenser on another dropper or dispenser. When you place droppers and dispensers to try to make it face south while looking directly at another dropper or dispenser, it does not face south.
Duplicate of MC-56957 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.