Missing feature: Searching with such filters as “Add to showing references”.
I do not know why useful features were left out of Endnote 20. It makes no sense to simply leave them out.
Another one: Although one can have a window open to enter a reference, you can only edit a reference in the side panel. That is not a feature. Please pass it up the line that this is an unwanted and severe limitation in the capabilities that were in Endnote 9 and previous versions. Taking it out makes no sense. Now I can’t compare notes in 2 or more, I can’t (easily) copy and paste between them, compare author lists.