Thanks Leo for the assistance.
However, "Enable Folder Content Type detection for" was not enabled. That option makes no difference whether enabled or not enabled.
I use a saved layout I made years ago that is "Dual display, dual trees" that has (among others) the columns "Size" in bytes, Files (total), Folders (total), and Path Length.
This layout is Perfect. I use DO more times in a day than all other programs combined in that day. It is how I can quickly verify restored files from computer backups on the company NAS.
Since your suggestion I've been testing some different scenarios and discovered that the problem is, at least in my situation, related to Path Length.
If the last character of the Path (directories + file name) is 287 chars or less, then the Lister does NOT change, regardless of the types of file in the last directory (.mp3, .mov, etc.).
However, if the Path Length is 288 or greater, then DO Always changes the Lister, regardless of the file type.
This is repeatable with both my backup software test suite of files and directories, as well as creating from scratch a test situation.
One note, though, sometimes clicking on a directory over the 287 Path Length for the First Time, the Lister shows a “normal” listing. But always, if you click on a directory up one or two levels, then click back down, the Lister will now change.
It turns out, at least in my situation, that it “seemed” (coincidentally) that the Lister change trigger were .mp3 files. After deleting the .mp3 files, the Path Length trigger of 287 chars remained.
Can you reproduce this?
Any thoughts on a fix?