I'm editing an .ipynb file in VS Code using the Jupyter Notebook extension. I can't seem to figure out how to collapse (or expand) cells.

Can someone explain to me how to do this (using hotkeys or not using hotkeys), or give ideas for what I might be doing wrong?

I tried each of the hotkeys shown below, under three sets of conditions: 1. with the blue vertical bar on the left-hand side of my cell input selected, 2. with the blue vertical bar on the left-hand side of my cell output selected, 3. with my cursor in my cell input.