I'm afraid I never got a solution to this. I did contact NCH but after several days of back and forth, they they were unable to help. They asked me to send them one of my scores which I did and they simply responded with "It worked for me" and stopped responding. I tried removing and re-installing, I tried installing on a second iPad (both iPad pro's) and it didn't work on that one either. I also reported it as a bug but got no response. Interestingly, I tested it on my iPhone and it did work, but that's obviously not desirable on such a small screen.
I'd love to get a solution to this but I'm not holding my breath 🙁
Rgds