The best part is the "intermittent" element. Been there, done that on different guns/platforms over the years.
How often is "occasionally?"
The fact that it's intermittent tells me that it's a tolerance/fitment issue. If something was truly broken, for example, it would well, be broken and always happen.
For fun, I would do the "mix and match" stuff you are talking about and take some notes as to what works with what.
If it was me sitting there on the floor trying to cipher this out, I would replace the striker, and while doing that take a look at that striker channel. Maybe some dykem or Sharpie on the relevant parts to see if your theory is right, that maybe things aren't engaging when they should be.