Found in

• Beta 117.0b9

Affected versions

• latest Beta 117.0b9
• Esr 115.2

Tested platforms

• Affected platforms: Win 11 x64, macOS 11, Ubuntu 22.04 x64

Steps to reproduce

1. Open https://mmec.ca/public-calendar/
2. Open the print preview
3. Either print, or "save to PDF".

Expected result

• The embedded calendars are printed/saved as shown in the preview.

Actual result

• The embedded calendars vanish as soon as you click the "print" or "save" button, and the resulting document is mostly empty.

Regression range

• Not a regression. This is fixed in latest Nightly (see Bug 1800897), but from some reasons the issue is still repo on Beta and RC builds.

Additional notes

• The issue does not seem to reproduce in Nightly 108.0a1, but it does in Beta 117.0b9 and ESR 115.2 builds, where the patch already landed. Also, the issue is not repro on all machines tested, for example, one of my college is not able to reproduce the issue on macOS 12 or Win 11 x64, but I am able to reproduce the issue on a different machines with Win 11 and macOS 11.
• Please observe the screencast with the issue.
• This is a follow-up bug found after verifying the patch from Bug 1800897. See more context in https://bugzilla.mozilla.org/show_bug.cgi?id=1800897#c21.