Unfortunately the way the listboxes work in the IDE has changed in VS2019 in C#, which is causing problems for our listboxes. We are currently working on this, to get our listboxes working properly again:
case=137431
Until then the setting has been removed, since it does not work in VS2019, but it still works in the earlier IDE's.
A fix is under active development. We had hoped for inclusion in build 2341, but that didn't pan out. We currently hope to have it addressed in the Aug/Sept timeframe.