How's it going, just to let you know I have to same issue you have. I know you been searching all over the internet cause I have as well and my search terms pops up your name EVERYWHERE!
Right now I have to same integration as you PMP with the WP affiliate platform, and only the initial payment is tracking I also need the ability to track recurring commission, with added ability to award commissions to the "original affiliate" who referred the person the first time they joined.
========= WHAT I NEED =====================
JIM REFERS BOB in the month of January, JIM earns $10 aff commission.
When BOB pays his February membership fee, I need JIM (referring aff) to earn again $10 aff commission. As long as BOB is paying his membership fee i need JIM to earn on every payment BOB makes.
If this what you were looking for as well, I'm willing to work together to get this done.
This is where I hang out cause Jason Coleman the creator of this plugin paid membership pro, always has the updates and latest fixes here I also have an account, you may want to signup for free and follow Jason. https://gist.github.com/strangerstudios
Discovered I dont know if this maybe right or what but a 2 days ago looks like Jason updated some code in the checkout.php process.
I wonder does this have anything to do with the WP affiliate platform code we are using.