In certain situations the ability unnerve makes berries not activating.
Testing situation:
Turn One:
Player 1's Galvantula paralyzes the Player 2's Kingdra with Thunder-Wave. Kingdra is holding a Lum Berry, but it does not activate due to Galvantula's ability, Unnerve.
Turn Two:
Player 1 switches Galvantula out to another pokemon, in this case, Magikarp. Kingdra's Lum Berry should activate upon Galvantula switching out of the battle, however, it does not consume the berry and continues to be paralyzed.
And here's a showdown replay showing you how everything should work:
http://replay.pokemonshowdown.com/customgame-530848068I'm here if some more infos are needed.
~ Xasah