I've seen this too, and I think I've figured out why.
The careers site appears to save fields as part of a blur event on the field.
What I imagine happens, is this:
- you type the first however many characters
- autocomplete dropdown appears
- you click the autocomplete dropdown
- blur event triggers on the input field, the content of the input field gets saved
- the content of the input field gets replaced from autocomplete.
Since another blur event doesn't get triggered on the field, the autocomplete data doesn't get saved.
The work-around seems to be not to use the mouse the select options from the autocomplete dropdown.