How can I get concurrent crew execution working

[FatherOfDragons]

I'm not quite sure whether this is a bug or a user error... I cannot get multiple crews to execute concurrently.
For example 'write_a_book_with_flows' example dies silently without any error traces when multiple WriteBookChapterCrew crews are started in order to write chapters concurrently.
Things work fine when I force serial execution, but as soon as there is any parallelism things break down. I get the same broken behavior when I try to run crews concurrently in a ThreadPoolExecutor.
Tried in the following environments:
MacOS Sequoia. Python 3.11.9
Debian GNU/Linux 12. (running in Docker). Python 3.11.10
Scanned bug reports and discussions, but did not see current mentions of similar issues.
Any help or advice would be greatly appreciated.