I have been trying to find an example in my day to day diaper experience that shows what has been going on with her dipes and I either only catch it when the dipe is completely soaked (so no point in taking a pic of that) or it doesn't happen....FINALLY caught it at the beginning. Here's the pic and you might have to tip your screen back to see what I'm saying (at least I do).

What is causing this "leakage" mid-diaper (not along the seams)?! Its driving me batshitcrazy!
Re: Okay THIS is what I'm talking about and need help!
Leaky PUL? Are you having this problem on a lot of diapers or just on a couple? I get this with some older covers that I have and I suspect (the PUL is hidden so I can't confirm) that the PUL has become damaged and degraded and causes moisture to wick right through the PUL which shouldn't happen under normal circumstances . . .
Do you dry your diapers or line dry? Are they older or newer?
I would also check out the PUL. It is probably cracked.
How old is the diaper? What kind is it?
The insert is probably absorbing just fine.
My guess is that the PUL has been cracked or streched so that liquid can get through. When you have a damp or wet insert sitting next to knit fabric (ie the outer of the diaper without the PUL) it is going to bleed through.
If they are less than a year old, I would contact the maker of the diaper and see what they suggest.