How can I figure out why Applications will NOT add to Dock?

I'm using the instructions from this question: How do I add my Applications folder to the dock?

In Finder, right-click on Applications on the Sidebar and select: Add to Dock

to add Applications to my Dock, however, nothing happens when I click "Add to Dock". I've also tried dragging Applications from finder onto the Dock next to Trash, but nothing happens. How can I find out what's wrong?

I'm on Catalina, 10.15.6 19G73

When you "right-click on Applications on the Sidebar and select: Add to Dock", nothing obvious happens if you have the Dock hidden, which is the default behavior. If your Dock looks anything like mine, after you add the Applications folder to the Dock, you might not even notice it.

When I right-click on Applications on the Sidebar and select: Add to Dock on Catalina 10.15.6, and then mouse down to the bottom of the screen to reveal the Dock, the Dock now has what looks like a new Application Icon next to the Trash Basket. It does not look like a folder at all. Instead, it is a stack of icons, with the top-most being the first (alphabetically) application in the Applications folder, so at first glance it looks like just another Application on the Dock.

When I hover over it, a label "Applications" pops up over it and when I click on it, it expands into a grid of icons representing all the Applications in the Applications folder. So that is the Applications folder in the Dock.

If I then drag the Applications folder from the Finder to the Dock, it disappears when I release the mouse, because the Applications folder is already in the Dock and you cannot have it duplicated in the Dock.