There are definitely some weird things going on re: motion blur and cloners. I have a rather complex grass-and-hills scene, where if I check the "object motion blur" option my road object starts to get really funky looking. In addition, random clones still lack motion blur frame to frame. I haven't gotten any crashes with motion blur lately though, so that's an improvement.
Overall I've been considering object motion blur broken for multiple builds now, and have only been using camera motion blur.
Attached are two renders: One with only camera motion blur on, the other with camera and object blur on. As you can see, as soon as object MB is enabled clones start losing textures, turning weird angles, and randomly missing MB as seen on one grass patch to the right.
Unfortunately I don't have time to simplify my scene, but I'll link it anyway. It has a similar setup to BigAl3D's endless road scene, just with more moving parts. It's also too large for the uploader, so I'll throw it on my google drive.
https://drive.google.com/open?id=18T32h3nVUBH2ew0IUJtWhN1NYaRqR6VyIf indeed the issue is related to lots of items attached to a cloner, particularly one doing repetitive cycles on a spline, I don't know if simplifying the scene too much would defeat the purpose.