Musescore 4 doesn't treat duplet notes correctly.

In 6/8 time, a duplet should take up half the measure (2 notes with the time of 3 notes); however, it is only taking up a 1/3 of the measure (2 notes with the time of 2 notes). Also, the beaming is all jacked up.
In this series of attachments, you can see the progress of trying to add 2 duplets to a 6/8 measure, which should use up the whole measure. When I try to add the second duplet, instead it adds one note to the previous duplet and closes out the duplet - not letting me add the second note.
I don't use duplet notes very often, so maybe I am doing it wrong.