Samsung
Create a New Calendar Event auf Samsung
The Samsung Calendar app does not create appointments on its own. It only displays events that already exist inside one of your synced accounts, so a missing entry usually means nothing has been saved yet, not a sync failure.
To add an event, follow this path: Tap on Calendar ➔ Tap on Add ➔ Enter a Title ➔ Set the Start/End time and other options ➔ Tap on Save.
On the same Add screen you can set a location, turn on a notification reminder, and attach a short note before saving. These fields are optional, so an event without a reminder simply will not alert you at the scheduled time.
If the event still does not appear on another device, check that the correct account was selected before saving. Events created under a local, non-synced calendar stay on the phone only and never reach linked accounts.
Use a messaging or dialer app instead of the calendar only when you need a one-time alarm for a call, since those apps do not offer recurring appointments, locations or shared notes.