Membership on Multisite & Recurring

I have a problem with PayPal recurring payments on a Membership Multisite install.
For some reason the recurring payments aren't recorded for subscriptions at any other site than the main site.
At the main site it works, being recorded in the subscription_transaction table for that site, and the expiry date of the subscription being extended properly.
However, subscriptions for members of any other site aren't updated when recurring payments are processed.
I have verified that the IPN notifications from PayPal are sent correctly, what the Membership plugin actually does with the notifications I have no idea, since they aren't recorded in any way.
The only transactions showing up in the transaction table is the original transaction, when they sign up.

What am I missing here?

Thanks,

-P