BoxHelper generates incorrect bounding box

Hi, I’ve been using Three.js for a project to prepare 3D models online for 3D printing. I’ve followed the solutions in similar questions but they don’t work. I’ve also taken a look at the Three.js editor itself, which actually also has this bug.

I’ll use the example from the Three.js editor. When I first load in my model, the bounding box is correct:

Then, when the object is rotated, the bounding box is incorrectly updated:

With the edges on the left side protruding more than they should.

Is it possible for BoxHelper to generate the expected bounding box? On closer inspection, it seems that a slanted bounding box is generated for the object, and the BoxHelper’s box is built around it. However, the code utilizes .updateMatrixWorld( true ) which should prevent this issue.

Thank you in advance. I’ve been wrestling with this bug for a few hours and can’t seem to crack it.

Here is the STL used in the demo:
Top Part Supportless.STL (930.0 KB)