Miraidon-ex ability sometimes can't select certain basic lightning Pokémon

Chaosmessenger

I have encountered a bug several times where I would use Miraidon-ex's Tandem Unit ability while my bench still had at least 2 empty spots, and in my deck were several different basic lightning type Pokémon, but clicking on some of them would not select them to be put in play by the ability.

In my most recent game, for example, I could select Regieleki V from my deck, but not Raichu V or Mareep. They all showed up among the "valid targets", but clicking on Raichu V or Mareep just didn't do anything.