Have no idea why your INR was settled in buyers favour.   But as stated, it has nothing to do with managed payments.

The  INR  policy  is separate to managed payments and applies to all transactions, even where the seller is not on managed payments.

Just wondering if the buyer actually lodged the INR with paypal,  Under managed payments in that scenario ebay would deal with paypal on your behalf, as you are not party to the paypal transaction.