Please delete your Saved and Intermediate files from your project folder. Then try to right-click within the Content Browser and ‘Fix up all redirectors’. Once you’ve done that, attempt to see if you’re able to cook or not. It may come down to you needing to recreate those few assets that are having trouble. Sometimes when you upgrade the engine, the file type changes too much and causes an issue with actually using it. Other times, the file may just need to be deleted and added back into the scene.
Once you’ve tried all of the suggestions I’ve given you, please upload any new as .txt files, as they’re easier to sort through that way.
Thank you!