Hello, I'm affected by this problem as well on bookworm (and bullseye before that).
Sébastien's suggestion did work for me, merci !
Nautilus properly (and promptly) generates all video thumbnails.
In my case, I needed to install:
* libopenblas0-serial
* libopenblas-serial-dev
in order to satisfy the dependencies of python3-matplotlib, while
removing libopenblas0-pthread.
Best regards,
Santiago
