Can't run Blazor studio even if SDK 8.0 is installed
That's correct. Radzen Blazor Studio would refuse to work when the latest version installed is a preview. We have encountered problems with preview frameworks in the past and decided to support only release versions.
There is a non-preview SDK 8.0 installed as well. I can't uninstall preview due to it being part of Visual Studio
We will add an option to use preview versions with the next release (after allowing it from the settings).