Replays - All they do is record the direction the gun was pointed when shot, they don't record every pellets direction. The hit marker in a replay is not based off the original recording but off of regenerated spread each time you play it back. If you really want to find the issue you need to start doing live recordings with OBS or XSplit or some other application and keep the bullet effects on. Someone had a twitch recording and that was the only reason i was able to find a very rare case of when a shot wouldn't register, but that was only for 1 very specific case which these do not appear to have.
There is hack that exploits the anti-lead that Taint mentioned, which is fixed in V8.
