First Frame Duplicated in Timeline, Last Frame Missing — Same Clip Plays Fine in New Sequence

Hi all,

I’m seeing a strange frame duplication issue in Premiere Pro with iPhone footage.

My clips vary slightly in frame rate according to the Project panel: 29.97, 29.98, 29.99, and 30.00 fps.

I created a sequence by right-clicking one clip and choosing “New Sequence from Clip.” This became the start of my dailies/stringout sequence. From there, I dragged all clips from that shooting day into the timeline, sorted by Creation Date in the Project panel so they would lay down chronologically.

After working from this sequence for a while and pulling selects, I discovered that many (but not all) clips appear to have their first video frame duplicated in the timeline.

Here is the behavior:

- Timeline frame 1 = Source frame 1  
- Timeline frame 2 = Source frame 1 again  
- Timeline frame 3 = Source frame 2  
- Timeline frame 4 = Source frame 3  

This offset continues through the entire clip.

I then checked the tail end of several clips. In each case, the timeline’s last visible frame matches the source clip’s second-to-last frame. The true final source frame is missing in the timeline.

So Premiere appears to be:

1. Duplicating source frame 1 into timeline frame 2  
2. Shifting all remaining source frames forward by one position  
3. Ending the clip one frame early in the timeline

Important detail:

If I take any individual clip from this same batch and right-click “New Sequence from Clip,” the newly created sequence plays perfectly with no duplicated first frame.

Both the problematic stringout sequence and the fresh test sequence show “30 fps Timecode” in Sequence Settings.

Questions:

- What could cause only one sequence to exhibit this behavior while another sequence created from the same media does not?
- Is this related to mixed near-30 fps iPhone media?
- Could this be a sequence timebase mismatch that is not obvious from Sequence Settings?
- Has anyone seen Premiere shift clip boundaries by exactly one frame like this?

I’m genuinely stumped and would appreciate any insight.