This bug occurs with me from time to time. Strangely only in one project. When I go to the Window tab, not all options are displayed, and the inspector does not work properly any more. For example, I can not enable or disable Game Objects. I hope someone can help me, because I can not continue to work.
I have deleted the automatically generated plugins folder and the problem was solved. Then I could download the folder again and the project worked smoothly.