Long notes in hidden tuplet passages

Hi everyone. I am working on notating a piece by Arnold Bax, where he often writes the orchestra in 9/8 but the solo viola in 3/4. I have overcome this with the pickup trick and hidden tuplets, but for long notes in this situation, Dorico insists on using several notes with ties rather than one longer note. For example:

Does anyone know a way to overcome this? Thanks!

Use a single 6:9e tuplet in each 3/4 bar (instead of the three shorter tuplets)

Thank you so much Janus!