I work with multiclips in different tracks. Shifting, copying, trimming multiclips works fine up to a point, when the system freezes (spinning color wheel) for about 3 to 4 minutes (Premiere Beta on M1 Mac mini 16GB) - I had the cache rebuildt, to no avail. When the crash happens is hard to predict, sometimes with a simple extension of the clip head or tail by 1 Frame … often after working for about 10 - 15 minutes. Auto-safe happens more often that the "soft-crash" occurs. "Soft-crash" means the systems recovers from it after 3-4 Minutes. There is one indicator of the crash happening: the audio wave forms disappear just befor it freezes.