Copy past error in clips that use audio effects (single band compressor specifically). Crash report
reproducable error / crash when dealing with copy pasting clips and sequences where clips have the single band compressor audio effect (and possible other audio effects).
any actual editing in a timeline where all clips have the compressor effect on them is so unreliable that the effects must be removed across the board until the edit is done, right before final export.
btw this is on a 2013 10.13.6 iMac.