How do I find (and clear) the missing space (25 GB) that is on my (main) Hard Drive?

Hi, all. I hope that you are well. First, I would like to thank you for reading and sharing any information that you have.

I don't know why I am missing space on my boot disk. I have read a lot of the posts (questions and answers) found in this forum. I have freed up about 35 GB by doing so, already. I have used OmniDiskSweeper, and it says I should have more space than Finder is showing me. I have turned Time Machine off and back on, again. I have re-indexed Spotlight.

I didn't retrieve any space until I used Onyx, and this rid me of plenty of old (cached) files. Now, since I am no longer left with 6 GB on my Mac SSD, I am not sweating. But, I cannot seem to find the rest of the missing space for the life of me. I'd like to be able to leave some more files on this drive (rather than using as many aliases as I have been). If you can help me, please do. Take a look at the image to see what OmniDiskSweeper and Finder tell me.

The only reason I can think of could be installing KODI and then trying to minimize the buffer issue. I configured it by following instructions found online to stream the data, rather than use a buffer cache. So, whatever I watched would be stored on a hard drive. I deleted the app within the same day. But, I don't recall anything else in the past few weeks that would make my iMac act differently. That's all I know, so far.

Thanks!