8va trills don't work
I searched for this topic and didn't find it, so has anybody reported that on the piano treble clef (for sure, maybe the bass clef also), trills do not work when they are for a note marked 8va (octave higher). The note just repeats itself and does not trill with the next higher note.
Comments
A little different results over here: 8va-trill notes are an octave higher on this system.
E.g., [8va trilled B4] would be expected to give B5 C5 B5 etc., but it results in B5 C6 B5 etc. This doesn't make sense. It's as if the programming applies the 8va to the tonic and its trill, but then applies the 8va to the trill again. Once a certain pitch has been reached, the trill note doesn't sound for lack of a sample, so it sounds as if the tonic is repeated like the OP noted. E.g., a trilled C6 under an 8va (2-ledger-lines above G clef under an 8va) repeats C6 because D7 has no sample to play, but the listener will notice that there is space as if it attempted to play a D7. All this also applies to trill lines and mordents.
Created bug report
https://musescore.org/en/node/172176