I'm running into a refund issue when testing in-app purchases in sandbox mode. I'm able to successfully purchase items but roughly 1 out of 3 times, when the refund window pops up, it says it cannot connect even though our webhook servers can verify the transaction id sent from apple. My internet connection is good and I've varied the wait period from purchase to refund from 15mins to 2 hours. Any help would be greatly appreciated.