Same here. Maybe you should report a bug at support.mendix.com
Sounds like a issue Mendix should take a look at. Take a look on support.mendix.com
I tried downloading Studio Pro 8.0.0 from https://appstore.home.mendix.com/link/modelers/ and that worked. Can you try if it is also working for you, and if that is not the case, can you tell a bit more about the steps that you do. So the url you use, the browser that you use, and when exactly this error is reported to you. Etc.