Dorico does not play eight 1/32 notes for a three-line tremolo of quarter-note length (see attached screenshot). Rather, regardless of tempo, it plays only four notes at a slower speed than notated, plus a rest. Can this be fixed?
There are some options for the maximum speed of tremolos on the Timing page of Playback Options; you could try experimenting with some changes there.
I did reply to your same post on FB 
Thanks, that’s it. I’d seen that but somehow missed what it meant. When set to four lines for unmeasured tremolo, three lines indeed play back as 1/32 notes.