Slashed grace notes before trill are played after the bar

(Dorico 5, NotePerformer 4 built-in sounds)

These grace notes are played before the bar, as they should:

However if the next note has a trill, the grace notes are played after the bar:


Dorico considers one or more adjacent grace notes to be attached to the normal note which follows them. When a trill is applied to that normal note, it unfortunately affects the playback of the grace notes. If you have Dorico Pro, this problem can be avoided by slightly postponing the start of the trill.

In your example, enter the grace notes followed by a 64th note, a dotted half note inside a 48:47z tuplet and a regular dotted half note. Tie the dotted half notes together and apply the trill to them as shown in the first staff below. Then hide the tuplet number. In engrave mode, select the 64th note and hide its stem, notehead and ledger lines. In note spacing mode, select the handle at the start of the tied note and move it to the left to get closer to the grace notes. In write mode, select the grace notes and the tied note, add a slur and flip it as shown in the second staff: