Mew ex missing attacks

Sometimes when I try to attack with Mew ex certain attacks on my bench do not show up as an option with Mew ex. For instance I had 2 psychic energy attached to Mew ex and a Lillies Clefairy ex on my bench and Full moon rondo was not an option that shows up. Next turn the attack did show up and I could use it. No other effects were on the board that would have stopped me from copying it. It wasn't that I couldn't choose that attack because of missing energy but that it did not even show up as a option I could choose.