I'm not sure whether this is the same issue, a different issue, or I'm just being dense.
I'm running Photomechanic Plus V6 build 4617 under Windows 10 home.
As far as I can see, the sort function just doesn't work, ever. Shown below are three screen grabs showing sort by filename, by capture time and modification time. Each thumbnail has three labels: file name, capture time, and modification time. (My default file naming convention is {datesort}-{seq}.)
As you can see, none of these sorts are correct. In fact, I think they are all the same.