I still see all the fields being updated in the code on my machine. Are you talking specifically about the == null check? If yes, since it was a string earlier the check was required. Not with it being a decimal it will automatically be 0 if the user does not specify it so null check is not required.

                        // Update the timeline fields
                        updateTimeline.Title = timelineRequest.Title;
                        updateTimeline.Regime = timelineRequest.Regime;
                        updateTimeline.FromYear = timelineRequest.FromYear;
                        updateTimeline.ToYear = timelineRequest.ToYear;
                        returnValue = updateTimelineGuid;