I can't reproduce this, most likely it is something specific to the score/selection you are working on. Please attach the score and give more precise steps to reproduce the problem (which measures to select, which voices to swap).
It happened with OSX Mojave 10.14.6
OS: macOS 10.14, Arch.: x86_64, MuseScore version (64-bit): 3.3.4.24412, revision: 7684abe
But it turns out not to be that reproducible anymore. Unfortunately the score with which it happened reproducibly is now changed and doesn't produce the crash anymore.
Comments
Crashes should be critical
Fix typo in issue title.
OS: macOS 10.14, Arch.: x86_64, MuseScore version (64-bit): 3.3.4.24412, revision: 7684abe
I can't reproduce this, most likely it is something specific to the score/selection you are working on. Please attach the score and give more precise steps to reproduce the problem (which measures to select, which voices to swap).
I can't reproduce it either, MuseScore 3.3.4, Windows 7
It happened with OSX Mojave 10.14.6
OS: macOS 10.14, Arch.: x86_64, MuseScore version (64-bit): 3.3.4.24412, revision: 7684abe
But it turns out not to be that reproducible anymore. Unfortunately the score with which it happened reproducibly is now changed and doesn't produce the crash anymore.
Reopen, if you can reproduce, with a sample score then ;-)