Burned-In Timecode Offset Error After Speed Change

I’m having a dreadful time figuring out a burned-in time-code with a Ring video in which I need to slow a 4 or 5-second segment. The problem is that even though the Offset and Starting timecode are set to all zeros, the starting value in the video is not zero when the Clip Speed / Duration is not 100%. I’m using Generate Timecode. Other than wrong starting timecode (-01:00:28:14), the displayed timecode works as expected; i.e. the frame number changes according to the original frames, not the interpolated frames.