When formatting time from hours and seconds, to more advanced format like h:m:s.ms, we should do it in a step-by-step format.
Click on an empty cell.
Right click on the result (1), and choose format cell (2).
Choose custom (1), write hh(tt in this case):mm:ss,000;@ in the field under type (2), and press ok (3).
The Time format would now look like this: