OK - so, here's the situation. In Mojave, I could drag and drop (or copy/paste) files from the desktop to "Macintosh HD." This specifically consisted of me creating a folder in "Macintosh HD" (next to where all the other major folders are - "applications," and so on). This folder would be "my" folder for files, downloaded DMGs, and so on. HOWEVER, in Catalina, I cannot do this. I cannot create a new folder in "Macintosh HD" where the main folders are (e.g., "applications"). I did research online, and found stuff to suggest this was perhaps a permissions problem. Instead of messing around, I decided to start anew and reinstall Catalina after erasing the disk in Disk Utility. (I use my MacBook Air for occasional stuff, so starting over wasn't a problem.) After I reinstalled Catalina on an erased disk to ensure it was a "fresh" reinstall, I discovered the same behavior with files/folders persisted. I was a little surprised. Is this a NEW thing with Catalina? Users cannot drag and drop OR copy/paste things in "Macintosh HD" where the main folders are? To be clear: I can, however, create folders and do the same things when in other folders within "Macintosh HD," like by going into my "Users" folder. Things are fine now; I've had to resort to a couple of workarounds to make the desired folder to be as accessible as it was in Mojave (for example, by making the specific folder in question a "favorite" in the sidebar in Finder, so it's right there when opening Finder). But again ... is this a NEW thing with Catalina? Keep in mind I did a fresh reinstall after erasing the disk, so what got installed was a fresh copy of Catalina with default options enabled. Thanks!