Xiaomi
Add Account in Calendar App auf Xiaomi
Xiaomi Calendar only shows events from accounts you have explicitly connected. If you switch phones, add a work email, or use a second Google account, the app will not pull in any events until that account is added under Calendar settings.
The setting lives inside the calendar app itself, not in the general system settings. Open Open Calendar ➔ Open the menu ➔ Open the Settings ➔ Tap on Calendar accounts ➔ Tap on Add account ➔ Choose Exchange or Google and follow the instructions.
Pick Google for a standard Gmail or Workspace account, or Exchange for most corporate mail systems including Outlook and Office 365. After sign-in, the calendar syncs automatically in the background and pulls in existing appointments within a few minutes.
If sync still fails afterward, check that calendar sync is enabled for that specific account inside your device account settings, since adding the account here only links it - it does not override a disabled sync toggle.
Removing an account later is done from the same Calendar accounts screen, but this also deletes any locally cached events tied to it.