I just switched grip modules on my full size from medium to small. After switching I dropped the magazine without a problem from the left side button and realized I had forgotten to switch it to the right side (I am a lefty). So I switched over the mag release button and then found that when hitting the button, the mag would sometimes not drop free or I would need to press it really hard to get it to drop.
I reinstalled the release button a couple of times and sometimes the mag would not easily insert or would not drop free.
So then I thought, ok, perhaps it is the release button or spring on the new module, try the one from the old medium size module which always worked perfectly after I switched it from left to right on the day I bought the gun.
So I deinstalled the mag release button and spring from the old module to the new one and it is still sort of 'sticky' and inconsistently does not drop the mag free.
This makes no sense to me, since the grip modules themselves should not impact operation of the mag release button. The module is a simply made on a plastic mold and should not make a difference.
Ok, geniuses, what stupid mistake did I make this time
PS: just tried a full mag and it worked perfectly, the two empty mags did not not drop free easily or consistently in the small module whereas they always did in the older medium