In addition to the above description, I have devised a workaround to achieve what I wanted, namely a quarter note followed by a quarter-note rest. Prior to this, all I could achieve was a quarter note followed by a quarter-note rest and a half-note rest, with the unwanted half-note rest being caused by some mysterious bug.
Start with a duplet consisting of two quarter notes ( ; 2:3q Enter).
Select the second quarter note of the duplet, press 5 to make it an eighth note and extend the selection to include the eighth-note rest following it.
Create a triplet ( ; 3:2e Enter).
Delete the eighth note (first note of the triplet) and select the rest which is created in its place.
Press O (letter) then 6 to force the rest to a quarter-note duration.
Select the eighth-note rest and choose Edit > Remove Rests.
Select the triplet bracket and delete it.
Select the duplet bracket, show the Properties panel (at the bottom). In the “Tuplets” section, click on “Number” and “Bracket” - this should hide the duplet bracket.
Click on the quarter-note rest.
In the Properties panel, in the “Notes and Rests” section, “Force position and duration” should be selected. If you click that off and on, the extra half-note rest appears and disappears. The quarter-note rest can be raised or lowered using “Rest pos.”. In write mode, the half-note rest does not move with it, even though when you select one or the other rest, both highlight at the same time. In Engrave mode, the rests can be moved separately (assuming that “Force position and duration” is de-selected, causing the half-note rest to show). Before enacting this workaround, any attempt at using “Force position and duration” or “Rest pos.” in the Properties panel resulted in the “Notes and Rests” and “Beaming” sections of the Properties panel disappearing.
It’s a bit of work, but until the errant behaviour is rectified I can at least proceed with my project.
