I’m having some trouble with adding/deleting additional fields and data changing keys.
Here are the steps to reproduce:
Fresh WordPress 3.9 install with TEC 3.5.1 and TEC Pro 3.5.2. WordPress Twenty Fourteen theme.
Navigate to Settings > Additional Fields. Add 3 additional fields named Field One, Field Two, Field Three. All Text fields.
Add New Event with title of Test and 3 additional field values: Value One, Value Two, Value Three. Publish Event. View Event. Everything looks good. Shows the fields/values.
Remove Field Two. Save Changes.
Refresh event front end. Only shows Field One. Doesn’t show field two or field three.
Edit Event. Notice that Field Three is empty. Put in New Value Three. Save Event.
Refresh front end. Shows field one and field three.
Edit Additional Fields. Add a new field called Field Four. Save.
Edit event. Field One has Value One. Field Three has New Value Three. Field Four has Value Three.
The keys shift around if fields are added/removed.