Calendar or event is not synchronized from the Android device to Thunderbird
When you create an event in Android stock calendar application, you can usually choose in which calendar you want to create it. But only calendars selected to be synchronized in BirdieSync options in Thunderbird or Sunbird are synchronized. It means that if you create a new event in the "Home " calendar on the Android device and that only "Work" calendar is selected to be synchronized, this event will not be synchronized.
BirdieSync also gives your the possibility to choose which Android event accounts you wish to synchronize. So if your event is still not synchronized, did you check that the account of the calendar where you created the event is selected to be synchronized in BirdieSync settings on the Android device ? You may access to these settings opening BirdieSync application, clicking on the "Settings" button and selecting the "Event" tab.
For instance, if you created an event in a Google calendar on your Android device and if this Google account was not selected to be synchronized in BirdieSync settings, this new event will not be synchronized. The solution is either to select the Google account to be synchronized in BirdieSync settings, or to create your event in another calendar belonging to a synchronized account.