Balls go through Zubats and other flying types?

Sorry if this question has been answered before. I am a level 23 player and I have become pretty proficient at catching Pokémon. All except the (very common around here) zubats and occasionally other flying types: The Pokéball goes through them when I release it. Hard to describe. My question is, whether others have noted this or is this my problem. Thanks.

Unless you're experiencing an extremely rare bug, I have not been able to find or reproduce balls going through Pokemon.

However, Zubat is notorious for having an extremely small hitbox:

CollisionRadiusM: 0.0535
CollisionHeightM: 0.0535
CollisionHeadRadiusM: 0.1605

It most likely is that your balls are just not hitting this target hitbox, which may have the semblance of a ball "going through" your Zubat and others.

You can also compare this to the hitbox of Pidgey:

CollisionRadiusM: 0.1344
CollisionHeightM: 0.252
CollisionHeadRadiusM: 0.126

Additionally, it may be a good idea to note that Flying Pokemon will tend to "wander" around the screen a bit more, causing their hitbox to be non-stationary, unlike their ground-type equivalents.

I don't know the code, but, I know that on slower phones (even slightly slower) you'll have to wait a couple of seconds before the game places their hitbox to be, well, hit.