[urbandw311er]

Had a similar experience myself recently with migrating the whole family over to iCloud calendar and having to import thousands of calendar events from iCal files. The process hung several times, repeatedly crashed the iCloud web client and Apple L1 support, while lovely, were out of their depth.

Logging and diagnostics were minimal and it really was a black box. Smelled very much like one poorly understood/under maintained server sat somewhere that deals with calDav for web.

I suspect that the most senior engineering teams at Apple that work on this stuff are pretty lean to say the least. Imagine a few ultra 10x guys who wrote most of the sync code base and now get hardcore salary incentives to NEVER LEAVE.