Search from UDW in File field in Form is blocked.

Steps:

1. Log in as admin to the back-office.
2. Go to Forms.
3. Create new Form.
4. Add the File field.
5. Open Settings.
6. Click button Select location.
7. Switch to Search tab.
8. Try to use Search.

Expected: Search works as in other places where UDW is opened.
Actual: Search is blocked, it's not possible to enter any phrase or press the button.