Hi, I continued to have this problem in 2020 and called tech support, they were very helpful. You need to dock palettes to the side margins one at a time. That is, if you have 3 palettes docked to each other, then try and drag them all at once to dock on the side margin, it won't work. I took the visualization palette, which I don't usually have open, and docked it to the side. For some reason it was easy to dock this palette when I had trouble with the others that I usually have open. Then I was able to dock the Basic palette to the side of the docked visualization palette. Then I could close the visualization palette and still have the Basic palette docked on the side. Then I could add my other palettes, one at a time, to the top or bottom of the basic palette. Not very straightforward, but it worked!