- When I add a new mapping to an existing Connection on an existing User Profile Service do I need to run a full synchronization, or is incremental enough?
- Is there any risk of losing data on the profiles such as the Photo, About Me, or Ask Me About sections when running a full synch, or does it only update the fields that are mapped to data sources?
Whenever a new mapping is made to User Profile service, Full User Profile Sync is required followed by incremental sync.
If there is no change at the AD then User Profile Incremental or Full Sync will not change it even the value is changed in the SharePoint.
User Profile Sync keeps track of the values that have been synced from AD to SharePoint. It does not re-sync values that haven't changed in AD since the last time they were synced to SharePoint. Since you changed it in SharePoint after it was already synced and didn't make changes in AD the value didn't overwrite your changes. It doesn't sync every value every time.
But if your AD connection is Two sync , import from AD and also Export from Sharepoint then every sync will update the value in AD if you change it in sharepoint