Sometime after 5/8/2013, my Yahoo calendar stop syncing with my iPad mini & iPhone 5. I had Yahoo calendar as the default calendar on both devices. I have tried all of the suggestions (deleting & re-adding, changing the fetch to 15 minutes, used the CALDAV add method & have exported from Yahoo into the iPad & iPhone). Nothing works! I read through the issues on Apples community support page, chatted with AT&T support (whos says that I need to log into Yahoo through Safari for the Apple device to recognized my identity). Ive also searched through Yahoo support, still nothing. Yahoo seems to lack an interactive support (an option to send an email with your issue) or I just cant find it. I have since change to iPad/iPhone calendar with iCloud back up, but it doesnt feel like the back up to the back up like syncing to the Yahoo calendar. Does anyone have any suggestions?