Are you still using the newborn insert, or have you switched to the one size insert yet? If you aren't using the os one yet, leaking was our sign it was time to do so.
ETA: I was half asleep when I read your post and completely missed the part about fabric softener. If the inserts weren't soaked you probably have a build up problem.
If he used fabric softener, it can coat the fleece and make them repel.
If that's the case, you'll need to strip with blue Dawn dish soap. I'm willing to roll the dice and do it in my machine; other people do it by hand and just rinse in the machine.
Is the insert soaked? If it is, add more stuffing. If it's dry and you're getting leaks, time to strip.
Agree with token. If the insert is soaked, then you probably need more absorbancy. If the insert isn't soaked, then there's something wrong with the diaper and it's repelling liquid.
If the problem is absorbancy, I would recommend trying some hemp or bamboo inserts for more absorbancy. I don't use microfiber at all anymore.