@uptempoguy - Well that should work, I was thinking you has an older release as Apple did have a few hiccups with the first versions of APFS when then changed over from HPFS+
At this point you'll need to try another tool, give this one a try [https://macdrive.com/|MacDrive] see if the free version can get at least ID the problem. You may need the full version or it could be the drive it's self has failed which will require a file recovery service to get your data off if you don't have any copies, it won't be cheap.