So I reported this issue to Maxon and started a dialogue with a representative … it seemed like they were prepared to look into the issue and told me that " there were issue on older versions on macOS"…
I heard back from Maxon this morning who told me…
“the solution to update to macOS 10.14. Actually we are not able to offer another solution.”
I was really disappointed with this, to be told they are not able to offer another solution. There’s clearly an issue with the navigation in R21 with a Wacom. I can hold R20 and R21 side by side, navigation in R20 works for me but doesn’t in R21.
Effectively I would have to sacrifice Redshift if I were to upgrade my Mac OS and Redshift is much too important a tool for me to consider losing it… and I have no guarantee that navigation will begin to work for me even if I do, so I’m not prepared to do it at the moment.
It would be useful if there are any Mac users out there who also use a Wacom tablet as their main pointing device to test the navigation. The issue I’m experiencing is explained above, but suffice to say that MMB and RMB aren’t working for me in the 3D viewport. When I say RMB I’m talking about ctrl click and MMB is set to the redundant function key on the keyboard. These buttons do register in the command manager and they will work for navigation in combination with a mouse, but not with the Wacom.
Unfortunately for me, this means either completely changing the way I work to accommodate or just not upgrading to R21.