How to reproduce:
1. Open the attached “IN-142276” project
2. Build and run the project (File -> Build Profiles, ensure Web is the active platform)
3. Observe the Player in the browser

Actual result: “Actual length” is lower than “Expected” and some writes are reported as missing or torn
Expected result: “Actual length” matches “Expected” and no writes are reported as missing, duplicated, out of range, or torn

Reproducible with: 1.8.26 (6000.5.0a1), 1.8.29 (6000.5.0b10, 6000.6.0a6)
Not reproducible with: 1.8.25 (6000.5.0a1)

Reproducible on: Windows 11
Not reproducible on: No other environments tested

Notes:
-This requires “Native C/C++ Multithreading” to be enabled in the “Publishing Settings”
-This issue only reproduces in the Player