Some of these have unfortunately been the fault of Apple's own iCloud drive sync problems in the past. I've noticed many apps that use it struggle to maintain consistent data across multiple devices in the case of conflicts / offline devices coming back online and having to catch up.
I changed to CloudKit and changed the extension as well to ".md". I was able to add a calendar event once or twice, then the same issue came up again where it could not add event and asked me to email support. I've deleted the app and reinstalled a few times. Anything else I can try?
1. Installing on second machine led to daily note being constantly wiped while I typed
2. Could not add/modify events to calendar
3. When entering a task I added '3pm-5pm' and nothing showed on calendar (probably related to #2)
Looks great, just don't think it's ready for prime time.