Disk space filling up and disk sweeper can't find files

I was using Adobe After Effects and my disk cache filled up tremendously, to the point I was getting warnings about my disk being full and applications started not working. I've experienced this before and clearing the disk cache would always do the trick. I cleared 102 GB worth of cached previews from After Effects, and checked the finder to make sure they were gone. When my disk was full, Disk Utility was telling me I had only about 10 GB of space left. Once I deleted the 102GB worth of AE cache files and emptied the trash, this only appeared to free up roughly 20GB, putting me up to 30 GB of free space, according to Disk Utility.

I ran Omni Disk Sweeper again, and it could only locate about 780 GB worth of data on my 1TB disk, which is what it was at before I was using after effects. Where is this other 200GB of space that none of my disk sweepers can locate? Are there any other cached files that After Effects creates? Or hidden files I need to access?

Photoshop and After Effects will actually open again after getting that 30GB worth of space, but Time Machine still refuses to perform an automatic back up to my external hard drive I have it set to, claiming the disk is full (which is strange because it's always technically full as Time Machine keeps creating and deleting back ups) This only started happening now.