The assert is valid and is indicating that something went wrong.
I was unable to repro the problem with one of my test worlds.
Can you point me to a reduced repro app that shows the problem? I should be able to debug it if I can reproduce the problem.
Are you doing any custom destruction handling or modifying _bodyList manually anywhere in your code? The CreateBody/DestroyBody are the only points where _bodyCount is modified in the engine so it should always be accurate unless something else steps
in to modify the list or the count directly.