Zen crashed (completly unresponsive - but without error) when I download (export) an STL file from OnShape

[Wunderflunder]

Preliminary Checks

• I have read and understood the important section above.
• I have searched existing issues and avoided creating duplicates.
• I am not filing an enhancement request.
• I have checked that this issue cannot be reproduced on Mozilla Firefox.
• I have checked that this issue can be reproduced once I removed all my Mods and Custom CSS.

What happened?

Most of the time - some times not - zen becomes unresponsive when I download a STL (3D model) file. It could have to do with STL being automatically executed via Bamboo Labs software on my PC. I have tested in Brave and firefox. I both cases it functioned as expected and did not crash the application.

Expected behavior

After pressing export on the file it should save into the downloads folder

Actual behavior

Zen has two possible behaivours: 1) Freezes completly (no download) 2) Freezes but also automatilcy starts my 3D printer software with the file

Steps to reproduce

Not completly certain on this one.

Simply create a 3D model in onshape, then in the parts menu left click your chosen part, export. It pops up an menu and after pressing confirm the browser freezes,
I have not tested if this behaivor changes if bamboo labs is deinstalled.

Screenshots and videos

Zen.Browser.2026-08-24.23-57-41.mp4

Version

1.21.15b (Firefox 154.0) (64-bit)

What platform are you seeing the problem on?

Windows - x64

What component is this issue related to?

Other

Relevant log output if applicable

[Wunderflunder]

I also tried downloading an .stl from https://build.openflexure.org/openflexure-microscope/v7.0.0-beta5/high_res_microscope/test_your_printer.html but this also led to the same failure