Playback precision

I’m still very new to Dorico but I’m going ‘all in’ and writing a new piece in it rather than starting in Finale and using XML. Members of this forum have been exceptionally helpful for which my heartfelt thanks. I have a playback issue with a fast section for arco solo cello and accompanying pizz. strings in which there are numerous time signature changes and accented notes. The solo part doesn’t play very accurately and is frequently a little bit behind and then it catches up and then it happens again, seemingly randomly. It’s driving me nuts! Any suggestions?

This must have to do with the virtual samples of the solo cello.
If you switch to Play Mode, Key Editor view, you can manually correct the exact beginning/starting point of individual notes (of your solo cello). This might help you get the desired playback