Also make sure you are not mashing the mag release hard. On my shadow, which comes from the factory with the ext mag release, if you mash the mag release to hard, the other side of the mag releases comes into the mag well and causes the mags to get hung up.
To check this take the top end off (slide and barrel), insert a mag with the round walked forward a bit, mash the mag release hard and it will get hung up, just lightly press it and they will drop free.