MultiAttack and Extra Attack Chance

How does this interaction work? I have +2 Extra Attack Chance on my off-hand which sometimes shoots extra bullets from my pistols. I have +2 MultiAttack from a socket on my amulet. Now I just seem to always shoot 3 bullets and the +2 Extra Attack isn’t doing anything. An I mistaken or was I misunderstanding what Multiattack was supposed to do and this is intended? Or an I blind and not seeing some other effect?

Q3: I have a multiattack +2 affix and a +2 extra attack affix. I tested it and when I shot there were ALWAYS exactly 3 arrows coming out, even though the number should vary between 3 and 5, depending on how many extra attacks i get. Is this intended? How does the interaction between multi- and extra attacks work?

This is posted on the developer Q and A.

My necklace on wizard isnt as well… Not even on stats page.