Although it may be a "bad" piece of software, I do not have the skills to create an alternative, so I am persisting with trying to make it work. Rigol support has been very responsive but we've not had success yet. As an aside, it looks like UltraSigma is working fine - I can take screenshots that represent what I see on the 'scope fine.
We have tried thorough uninstalls of UltraSigma, UltraScope and all the NI / VISA gubbins it relies on, using the advanced mode in Revo uninstaller to remove leftover folders and registry keys etc. They also sent me version 1.2.13 of UltraScope, which I could not find on any of the Rigol download pages (all 1.2.12 or lower) but that did not fix the issue. The other thing they say to check is that .net 3.5 is installed correctly. Although they are still working on getting me a check so I can see if I have my machine set up with .net correctly, I have looked at some online guides and I think it is. No joy.
The NI software digs itself deep into the system and several people have struggled to remove sufficient proportions of an installation to be able to do a "clean" install of a different version, for troubleshooting. While I was eventually able to do this with Revo uninstaller and many reboots, there is a
thread here about how to attempt this with built-in windows uninstall tools. They didn't touch the registry, which Revo does, and I think is essential to being able to do a clean install.
Other things they think might contribute but haven't been in my case: check you have installed the UltraSigma and UltarScope are installed in a "Program Files" folder. In my case, they were in "Program Files x86". Also check that you use an admin user account.
I will report back with any other things they recommend to try and hopefully a fix. If anyone knows any alternative software that can do similar functions for the DS1054Z, please link it here.
So far these threads
here and
here seem to have good suggestions, including DSRemote, GazeAt and Sigrok/Pulseview. I'm on Win10 without any WSL/VM set up at the moment but I'm close to jumping ship.