No prob Leo. Honestly ?! I made it with the Stream Deck. I clicked on the tied note in the lower voice, then Strem Deck 8va. Then I clicked on the tied note in the upper voice, then Stream Deck 15ma…and the things ‘went wrong’. With the Stream Deck you don’t have the alt+enter of course…I think that’s the problem. I’ll check tomorrow.
Ah! You could add in Alt+Enter if you wanted, as a separate hotkey within the multi. Obviously there are plenty of situations (probably most) where you wouldn’t want Alt.
Yep, I knew that I could add it but it’s like you say: too many occasions where you wouldn’t need/want it…of course you could create 2 different kinds of 8va, 15ma keys 
You see Leo, I just know now what the problem was - thanx to you. So next time, in a similar situation, I won’t use the Stream Deck. I’d do it handish