Steps to reproduce:
1. Upload/ingest a test video file and wait for the workflow is finished
2. Open event metadata in the admin UI (tested with english language selected)
3. Change any fields
4. Reopen event metadata tab
Only changed metadata fields should be updated.
The start date is set to 2001-01-01 00:00 (an empty value in JSON response).
This happen only by first metadata update. On second and following updates it is working fine.