Some thoughts from our prioritization:

• This is related to T166699 about performance, when I do that investigation I'll have a better idea of what's happening here
• I've heard things about our ~40MB files being definitely problematic, so it will be good to see where the drop-off point is.
• It might be good to rasterize the 3D model at a large bucket size right away (after upload), so we can downscale it instead of re-rendering every time we need a thumbnail.

I haven't been able to reproduce this on beta or on my machine, even with files up to ~150MB.
That said, a thumbnail does not appear for 3D uploads. It either says "Uploaded", without displayed a thumbnail, or "The upload succeeded, but the server could not get a preview thumbnail."

It seems that thumbnails failed to load because their mime type was unknown.
Since https://gerrit.wikimedia.org/r/#/c/336454/, the mime type for STL files is accurately being detected and thumbnail generation now also works in UW.
I've tested on my local machine with bin & plain stl files, from 11K to 40M+, and thumbnails seemed to generate just fine for all of them.

Hello, just checking on a few things. I believe that I have reproduced the issue on Beta.

Steps:

1. Went to https://commons.wikimedia.beta.wmflabs.org
2. Selected Upload File
3. Used the Upload Wizard to add a file (about 644KB)
4. On the upload page after adding the file the thumbnail is a simple icon (See pic 1)
5. Eventually the broken thumbnail icon appears (see pic 2) and that icon continues to appear while finishing the upload

Pic 1

We believe we have a fix for the root cause, possibly some time this week. Heads up, @ABorbaWMF.

Should be done, but can't be tested until completing T170444: On beta commons, thumbnailing of 3D files is broken still