Good at coursework and learning background material, but attempts at original research go downhill. How to overcome psychological block?
It is hard to give a good answer here, but it seems to me that you, despite being a good student, haven't learned to do research yet.

When you describe what you are good at, you describe all the things you need to be a good student. These things are all necessary to be good at research, but alas, they are not sufficient. To do research, you need to shift to a different gear.

For example: Do not read a paper thinking "How does this work?" but more "What does that mean? What can I do with it? What could be done differently?". Learn to read articles and books through different lenses, e.g. with a lens that focuses on broad understanding of concepts, a lens that focuses on fine details, a lens that focuses on open problems or possible improvements,…

Also, find a problem to work on, not a topic to learn. Ask some supervisor to provide a problem to work on at the beginning, but note that later on you should come up with interesting problems on your own.