Hi @colingorton, you should not need to use the tobii nuget packages if you are targeting UWP. The eye tracking APIs are built into the Windows platform from the start. I would suggest to remove the tobii nuget package and see if it still works.
I suspect that the issue that you ran into on the other machine might be something else. If you run into it again, please check which Windows build that the failing machine have (version 1803 or 1809). You can find it by running winver.exe.