[Regression]: Tracefile is missing actions in traceviewer although size of trace and length of recording in metadata suggests complete trace

[TBRSAFA]

Last Good Version

1.44.1

First Bad Version

1.45.0

Steps to reproduce

Unfortunately I can't provide a repo with reproduction since the AUT is an internal app and I can't easily strip our node project down to the bare minimum. When you need to know certain options/settings I can provide them ofcourse.

The described problem is always reproducable in 1.45.0 (and 1.45.1) regardless of the following conditions/settings:
headless: true/false
browser: chrome/safari
trace options:

• screenshots: true/false
• snapshots: true/false
• name: undefined/"foo"

See attached tracefiles for a (minimal) example in 1.44.1 en 1.45.1.

Expected behavior

Tracefile shows all actions during test.

Actual behavior

Tracefile doesnt show all actions during test.

Additional context

see attached tracefiles
1.44.1.zip
1.45.1.zip

Environment

System:
    OS: Windows 11 10.0.22631
    CPU: (20) x64 12th Gen Intel(R) Core(TM) i7-12800H
    Memory: 16.43 GB / 31.68 GB
  Binaries:
    Node: 20.12.1 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.22 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 10.5.2 - C:\Program Files\nodejs\npm.CMD
  IDEs:
    VSCode: 1.90.2 - C:\Users\TBR\AppData\Local\Programs\Microsoft VS Code\bin\code.CMD

[TBRSAFA]

We start the trace using this snippet:
await context.browserContext.tracing.start({
screenshots: true,
snapshots: true,
sources: false,
title: description,
});

where browserContext is of type BrowserContext and created as thus:
const config: BrowserContextOptions = {
bypassCSP: true,
viewport: null,
reducedMotion: "reduce",
acceptDownloads: true,
ignoreHTTPSErrors: true,
};
await context.browser.newContext(config);

[mxschmitt]

We unfortunately need a reproduction in order to triage issues / regressions. We can keep this issue open for a few days - but without a reproduction, we can't act on it. Thanks for your understanding.

[mxschmitt]

Update: We received similar issues the past 48 hours and it seems like there is a regression. I'll keep it open until the fix is confirmed, but it looks like #31541.