Motion and Transform Position keyframes do not update correctly with Nikon Z6 III HEVC 10-bit 4K100 clips in Premiere Pro 26.2.2.

Problem

Motion and Transform Position keyframes do not update correctly when editing Nikon Z6 III HEVC footage.

Steps to reproduce

1. Open Adobe Premiere Pro 26.2.2 (Build 3).
2. Import a Nikon Z6 III clip recorded as HEVC (H.265), 10-bit, 4:2:0, 3840 × 2160, 100 fps, Rec.709, Full Range.
3. Create a new sequence and place the clip on the timeline.
4. Select the clip and open Effect Controls.
5. Enable Position keyframes under Motion.
6. Create several Position keyframes and change the Position values at different points.
7. Move the playhead back to previous keyframes.

Expected result

Each Position keyframe should preserve its own value and the image should update correctly at every keyframe.

Actual result

After creating several Position keyframes, the image becomes stuck on a previous position or displays a different position from the selected keyframe.

Changing the numerical Position values no longer updates the image correctly.

The same issue also occurs when using the Transform effect instead of the intrinsic Motion effect.

Deleting the Motion keyframes restores normal behaviour, but the issue returns after creating new Position keyframes.

Tests performed

- The issue also occurs in a new Premiere project.
- Removing Time Remapping does not solve it.
- Disabling the Motion Graphics Template does not solve it.
- Disabling hardware H.264/HEVC decoding does not solve it.
- The issue does not occur with Premiere graphics such as a rectangle.
- The issue does not occur with downloaded H.264 video files.
- The issue disappears completely after transcoding the original Nikon Z6 III HEVC clip to Apple ProRes 422 using Adobe Media Encoder.

Source media

Camera: Nikon Z6 III
Codec: HEVC (H.265)
Bit depth: 10-bit
Chroma subsampling: 4:2:0
Resolution: 3840 × 2160
Frame rate: 100 fps
Color space: Rec.709
Range: Full Range
Audio: 48 kHz, 24-bit stereo

Premiere version

Adobe Premiere Pro 26.2.2 (Build 3)

Operating system

Windows 11 Pro 64-bit 

Hardware

CPU: AMD Ryzen 7 7700X (8 cores / 16 threads)

RAM: 32 GB DDR5

GPU: NVIDIA GeForce RTX 3060 12 GB

Storage: NVMe SSD

DirectX: DirectX 12 

The issue is reproducible every time using the original Nikon Z6 III HEVC clips and disappears consistently after transcoding the same clips to Apple ProRes 422.

This indicates a possible issue with Premiere Pro's handling of Nikon Z6 III HEVC media rather than with the Motion or Transform effects themselves. 

Video demonstration (Video demonstration ) 

The attached screen recording compares the exact same clip in two different formats.

Part 1:
Original Nikon Z6 III HEVC (H.265) 10-bit clip.
Creating multiple Position keyframes causes the Motion and Transform effects to stop updating correctly. The image becomes stuck on a previous position even though the Position values continue to change.

Part 2:
The exact same clip transcoded to Apple ProRes 422 using Adobe Media Encoder.
The Motion and Transform effects work normally, and Position keyframes update correctly.

This comparison demonstrates that the issue appears to be specific to the original Nikon Z6 III HEVC media. 

No project settings were changed between both tests. The only difference is the source codec.