Video clips become black with audio after save/reopen; saved source In/Out points are corrupted (Premiere 26.3, macOS)

Issue

Some phone-recorded video clips in an edited sequence became completely black while their audio continued to play normally. The timeline had worked normally for several hours. The problem appeared after saving the project, closing Premiere, and reopening it.

This was not damaged media or a simple decoding failure. The original MOV files decoded successfully from beginning to end and displayed correctly in Premiere's Source Monitor. Inspection of the saved .prproj data showed invalid source InPoint/OutPoint values on affected video clip objects.

Environment

- Adobe Premiere Pro 26.3.0
- macOS 26.5.2 (Build 25F84)
- Phone-recorded QuickTime MOV media
- HEVC Main 10, 3840 x 2160, 10-bit 4:2:0
- HLG / BT.2020 (arib-std-b67, bt2020nc)
- Nominal frame rate: 23.976 fps; measured average frame rates varied slightly between files

Steps that led to the issue

1. Import multiple long phone-recorded MOV files into a Premiere project.
2. Use portions of those files repeatedly across an approximately 43-minute edited sequence.
3. Edit normally for several hours; the phone footage displays correctly.
4. Save the project and close Premiere.
5. Reopen the saved project.
6. Some video segments from the phone files are now black, but their linked audio still plays.

I have not yet reduced this to a clean, deterministic reproduction project. The saved broken project and a repaired copy are available for private engineering analysis.

Expected result

Every video clip should retain its source InPoint/OutPoint and display the same frames after saving, closing, and reopening the project.

Actual result

Some video clip objects reopened with invalid source ranges and displayed black, while audio remained normal.

Diagnostic evidence

- 279 active placements referencing the relevant phone media were inspected.
- 195 unique video clip objects had invalid source-range values: phone file 2 had 35 placements, phone file 3 had 7, and phone file 8 had 153.
- Another phone file in the same project had 75 placements with normal values.
- The affected entries contained negative, reversed, or duration-inconsistent source ranges.
- In the affected clips, the old OutPoint consistently corresponded to the intended source-start position.
- Repairing each affected video clip by using the preserved value as the new InPoint and recalculating the OutPoint from timeline duration and playback speed restored the image.
- After repair, all 279 placements passed source-range and duration checks, and all repaired ranges were within the original media durations.
- A structural comparison showed that only the 195 video clip InPoint/OutPoint pairs were changed; timeline positions, audio, captions, effects, and other project data were unchanged.
- The repaired project was saved by Premiere, closed, reopened, and checked again. The repaired phone footage remained visible and the invalid-range count remained zero.

Troubleshooting already performed

- Confirmed the original MOV files were readable and not damaged by full-file decoding.
- Confirmed the original footage displayed correctly in Premiere's Source Monitor.
- Temporarily disabled hardware-accelerated H.264/HEVC decoding; it did not address the saved range corruption.
- Created and attached ProRes proxies after the issue occurred; proxies did not repair the invalid saved source ranges.
- The export option to use proxies was confirmed off.

Related report

This may be related to “Video clip in-points reset to zero after saving and reopening (Premiere Pro 26.2),” although the visible result here was black video rather than a reset to the first frame. I cannot yet confirm that both reports have the same trigger.
https://community.adobe.com/questions-579/video-clip-in-points-reset-to-zero-after-saving-and-reopening-premiere-pro-26-2-1624190

Files available privately

For privacy reasons, commercial project names, participant names, captions, and media are not attached publicly. I can provide the saved broken project, repaired project, before/after InPoint/OutPoint data, and approved media samples privately to an Adobe employee if needed.