In general, make a rest that is the same duration of the entire tuplet. For example, if you want the tuplet to last a total of 2 beats, make a half rest, then create your tuplet from that rest and then enter notes as normal. You can successfully enter notes up to a dotted half note or as short as you want in this example.
Comments
https://musescore.org/en/node/276045 ?
But maybe I didn't understand.
In general, make a rest that is the same duration of the entire tuplet. For example, if you want the tuplet to last a total of 2 beats, make a half rest, then create your tuplet from that rest and then enter notes as normal. You can successfully enter notes up to a dotted half note or as short as you want in this example.
If you need a duration that cannot be normally expressed using a single rest, then see https://musescore.org/en/node/260646