Hello folks, I signed up here just to add this comment. I have a 2019 MacBook Pro 16". Sketchup Make 2017 has been running fine on it. I upgraded to Big Sur a few days ago and opened Sketchup for the first time just a few minutes ago and had the upside-down dimensions. I’m using metric settings.
I of course tried rotating the objects but that didn’t work. Then I started searching online and found this. Very strangely, after a few minutes when I switched back to Sketchup, my dimensions were OK. There was no visible changeover so I can’t say when it happened - behind the scenes while searching or when I switched back.
I just clicked Undo to undo the rotation and the measurements are still displaying correctly. I have also just saved the file, closed it and closed Sketchup, then reopened, and everything looks normal.
I know this isn’t much help but it might be useful to know that it can come right.