Thank you for the information. I have a couple more questions for you.
Questions:
Could you check your Engine C++ Classes to make sure that you have the classes in the image below? (You will need to go to View Options and check show engine content to true)
Have you made any changes to your config files?
If you delete your config folder, saved folder, and intermediate folder, does this make a difference? (You may want to make back ups of these folders)
I ran into the same problem recently after upgrading a project. The solution is to ensure you have Environment Querying System enabled under Experimental in the Editor Preferences.
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