JULIAwj If this has only happened one time, you might be able to ignore it. If it happens again though, please let me know whether the two instances had anything in common: what you clicked just before, what your sims were doing or what lot they were on, anything on-screen that's unusual (wild horses, aliens, whatever). And let me know what world you've been playing in as well.
The fact is the game doesn't run perfectly in macOS. It runs "fine" for the most part, but there are issues here and there that the Windows version and the old 32-bit Mac version don't have. That doesn't mean that any issues are unfixable, only that the experience isn't going to be perfect.