Does disruptor flute not work on some commanders or was this a bug?

tried to use disruptor flute to make someones cloud strife go from costing 7 mana to 10 and i could not find his commanders name despite it being in the command zone the only enchantments down were war effort and war leaders call on his end, other context is there were no creatures on the field for the both of us. Can you only use disruptor flute on a commander that hasnt been summoned before? The only times i have used it so far is when i get it out before someone ever brings their commander to the field.