There have been emails from both stating an issue with the software and that there will be a delay see below for latest.
"Unfortunately, due to technical difficulties this month, December 2018 payments to Paddy Power Betfair partners are going to be delayed. The reason for this is that we are currently upgrading our Netrefer Affiliate Software and this led to an unforeseen technical problem which disrupted our monthly payment process. We are working as hard as we can to get payments processed and they should be with you soon and they should hit your account same day (Thursday/Friday) for UK/Ireland partners or a few days later for International partners.
We sincerely apologise for any inconvenience this will cause you. It was a matter that was out of our hands and the payment process will return to normal schedule next month."
I like it when it goes via bank transfer, but I do not use Skrill and from what I am reading over on GPWA there are some issues going on having a Skrill account.