This is a SERIOUS, but "inconsistent" bug.

Sadly, I do not have good instructions yet for exactly how to reproduce it. However, it has happened several times to me, and for more than one person, too.


THE SITUATION:
a) Sometimes when doing a "Save MI Scene" process for a series of frames, the export process will suddenly stop generating the ".scene.mi" files.
b) Once that occurs, it will continue to omit the .scene.mi files for the remainder of the export process
c) Doing the export again, for the same frames in the same project, will usually work fine
d) It can fail from the very beginning, or the problem can appear in the middle of an export
e) This does not happen often, but it's a serious problem

If there is anything I can do that might help isolate this bug, please let me know. I have not used the "dump file" utility for this, because it does not crash, but I can have that on if you think it will help at all.


MORE INFORMATION:
1) Picture #1 - You can see the .scene.mi files are missing... in this case you can see the failure started immediately, but sometimes the problem appears part way though an export process... you might export 90 frames fine, and then suddenly it stops writing the .scene.mi files
2) Picture #2 - Re-exporting the exact same frames, exact same settings, exact same project... worked the second time
2) Picture #3 - User "4u2ges" shared this picture when he encountered the problem, but notice he is also missing the .resource.mi file
3) User "Animagic" recently reported a problem related to Camera Changes and SpeedTree. Although his issue is somewhat similar, his was reproducible, and he was missing TWO files, not only the .scene.mi file, and my issue is not related to camera switches. So I am quite certain these are DIFFERENT issues, but I'll cross-reference them for your convenience.
Link: https://www.reallusion.com/FeedBackTracker/Issue/Scene-with-SpeedTree-causes-Iray-render-export-to-fail-at-camera-switch