I was able to open my yahoo calendar on Chrome or Edge, and it was perfectly synced. Now the multiple calendars I use for various events are not available on my iPhone and the calendar is blank. They show fine on all my PC browsers. I deleted my Yahoo account and readded with no success.
iPhone 5c, iOS 10
Where are calendar events stored? Not on iCloud?
You have not mentioned where your calendar events are? Google, iCloud, AOL, Exchange, Outlook, Yahoo or any Other
Refer to the pic below, you may get your answer
Which is your default calendar? Settings > Calendar > Default Calendar
Settings > Calendar > Sync > [All Events] - Watch the GIF below
I've done this twice. The My Yahoo Calendar automatically carried over to open in my Google browser on my iPhone, WITH all my "calendars' events" showing, including the left panel list of these calendars. They are all now missing and the calendar is blank.
Add the Yahoo calendar to the iOS mail app and enable yahoo calendar. See the pic below which is self-explanatory
Lost synced events for my yahoo calendars on iPhone
