”Other” Storage takes up 199GB of 255GB Hard Drive?!?

Do you have any local Time Machine snapshots? Try the following in a Terminal window:

tmutil listlocalsnapshotdates

Does it return any information?

Good luck...

You can download Omni DiskSweeper:

https://www.omnigroup.com/more

DiskSweeper can give you a more accurate read of disk space than Finder or Storage Tab of About this Mac. It can also show you the precise size and location of all your files. It will inventory your disk starting from the files that take up the most space. If you want you can even delete files from OmniDisk Sweeper. But be careful some of the items may be important to your system.

I can only account for about 32GBs partitioned for Windows and another 12GBs used by the other four partitions used by APFS. I don't think the APFS snapshots would consume that much space but no way to tell with Disk Utility.

I am gnawing on the possibility that space is somehow associated with the conversion from HFS+ to APFS. When you went through the macOS upgrade to Mojave or Catalina your SSD was converted from HFS+. Were there already files on the SSD before the conversion? I don't know a great deal about APFS and HFS+ conversion. Apple hasn't provided a great deal of documentation for those of us who are not programmers. I'm not that technically educated. I have a general understanding of APFS but that's it. My thinking is that I have no idea what this hidden space is nor why there's so much of it. It's just above my pay grade. Were this me, I would probably backup my files, boot from my emergency backup, erase that SSD completely, and reinstall macOS from scratch. Otherwise, you can fill up the disk over time and see what happens. Maybe all that space is under macOS control and will be released as you need it. Or, you will fill up the disk until the disk full alert at which time your only option will be to perform an Erase and Install.

Catalina will want to format an SSD using APFS which I agree is a better choice than HFS+. I've read that there is a noticeable improvement in overall disk speed plus the addition of snapshots that help with disk recovery, file copies, etc. I use it here on quite a few different SSDs and find it reliable. No problems thus far.

I am totally opposed to disk or file encryption. Too many things to go wrong, and if you forget the password, then you are SOL. I never encrypt. If I have something to protect I keep it in a safe deposit box and hope we don't lose the key!! I understand about being security conscious but I worry about losing everything when I forget the password and can't remember where I wrote it down. And, if you have to write it down, then you still have no security. But you should make the decision best suited to your needs. The above is just my opinion.

No case-sensitive. macOS does not require or use it. Stay away from it.

Partition Map is GUID.

Well, I guess you've tried all the utilities now. It's not showing nearly as much used storage as the system is reporting.

https://blog.macsales.com/51838-how-to-clean-install-macos-catalina/

What is 'Other' and 'Purgeable' in About This Mac?

Files That Make Up the 'Other' Storage Category, and How to Remove Them

Get Correct Storage Information

Do not use the information from the Storage section of the About This Mac dialog. Ignore the Storage information as it is typically wrong. To find out the correct information for any disk: Select a Desktop disk icon. Press Command-I to open the Get Info window and look at the topmost panel displayed. You will find the disk information displayed for Capacity, Available, and Used. If you have more than one disk/partition then repeat for each one on your Desktop.

The categories found in the Storage section of About This Mac is simply an arbitrary way of displaying files on your drive. There are no such categories actually on the drive.

There is no way we can tell you what hidden files are on your computer. Possibilities include Time Machine local snapshots and APFS snapshots, application data, etc. You need to make hidden files visible in order to see them:

Enable Finder to Show Invisible Files and Folders

Open the Terminal application in your Utilities folder.  At the prompt enter or paste the following command line then press RETURN.

defaults write com.apple.finder AppleShowAllFiles TRUE 

killall Finder

To turn off the display of invisible files and folders enter or paste the following command line and press RETURN.

defaults write com.apple.finder AppleShowAllFiles FALSE

killall Finder

Alternatively, you can use one of the numerous third-party utilities such as InVisible or ShowHideInvisibleFiles - MacUpdate.

While you have Terminal active you might see what is displayed by entering: diskutil list. If you have an APFS formatted disk, then this will show information on the invisible partitions it creates.

You can also get a different picture by opening Disk Utility in the Applications folder. On the top left is a small dropdown menu labeled View. Select the option to Show all Devices. This will provide a full view of how the disk is configured.