[BUG] Gengar ex's ability affects both sides

I just had this problem with Gengar ex where it's ability, Shadowy Spellbind, affected both me and my opponent when it's only supposed to affect my opponent. It's description reads, "As long as this Pokémon is in the active spot, your opponent can't use any Supporter cards from their hand." This also cost me a match because I was unable to use Sabrina to deal damage to my opponent's low HP Pokémon.