Can't change stem direction

In a 3/4 measure I'm trying to move three triplets from the 2nd voice to the 1st voice.

After some operations on the measure I have a series of triplets in the second voice which I move to the 1st voice using Tools->voices. When I try to change their stem directions the triplet 3 marker moves but the stems do not. See attached file.

measure:
1. original measure
2. remove dotted half note in 1st voice
3. Exchange voices to get triplet notes into 1st voice
4. delete 2nd voice rest
5. Measure 5 shows the result I get when trying to change the direction of triplet note stems. I tried selecting the whole measure then in the inspector I choose the notes button leaving all the notes in the measure selected. Now if I try to use stem direction chooser in the chord group I get the result in measure 5. If I choose the stem button it deselects all the notes. If I change the stem direction anyway it gives me the result in measure 5 but with only the first triplet changed.