We found that since the new windows version the two PREspective dll are deleted by windows defender. We are working on a more permanent fix but for now:
Go to your action center
Click on threats found
For the two dlls
Click on restore (make sure your unity editor is closed).
Restart your unity project.
Now we have to reset the .meta files to the correct configuration
Click on Assets\Plugins\PREspective\Edr\PREspective.dll inside the unity editor, then configure it as defined below.
then click on Assets\Plugins\PREspective.dll and configure it as defined below.
You should now be able to continue working with perspective. If there are still errors please contact us.