TOM

Right, async_get_events will not go through the Throttle; I did try that once a long time ago, and I don't recall if HA crashed or if HA just hung for...

That's to protect against multiple threads changing the opener at the same time. I suspect that works. If your calendar files are small enough and the network connection fast enough,...

Awesome! I’m glad that works. Thanks for your huge amount of help!

If O365 uses RFC 5545, then it can be assumed that all-day events are always in the local time zone.