I noticed the "pay in 4" option last month and started taking advantage of it. Had no problems with the initial payment but recently all other payments started to fail. I received messages that the payment failed even though the payment status updated to 2 of 4, 3 or 4, etc... (although it would eventually reset back to 1 of 4). Turns out the issue is with Capital One cards. They are now blocking "Pay in 4" payments according to THIS article. I switched cards and no further issues with Pay in 4 payments. I hope this helps somebody and keeps them from wasting their time with Paypal support.
