My experience with nailers is nil. So my comment can be out of thread here, if it is so please forgive me.
However, having put quite a lot of nails in my life, (same as most of you) and I do not want to sound pedantic; this thing tends to happen ( with normal nails) when the tip of the nail digs into the wood between the fibers of the grain separating them due to the shape of its tip and hence it is forced/driven to follow the easiest path, that is the soft fibres.
We all know that in order prevent that,the easiest thing to do is to flatten a bit the tip of the nail so that it breaks the fibers when digging in rather than separating them.
It is a tip I learnt long time ago but we tend to forget those things, obviously it may not apply here because nailers are a different thing but who knows?
Maybe just flatenning the the tips of the cartrige with a file or a grinder could help.
If you all knew that please disregard, I just though it could help.