I have just witnessed the strangest behavior on my windows 10 notebook. It is the second time it has happened. The first time I was sure that I did something but this time I am sure of what I did because I was very careful. For brevity I have substituted logical names. Thank you for any insight one what happened.

Here goes: Sub-directory ".\top" with sub directories .\top\sub1, .\top\sub2 and files .\top\top-f1.mp3, .\top\top-f2.mp3. sub1 has sub1-f1.mp3 and sub1-f2.mp3. sub2 has sub2-f1.mp3 and sub2-f2.mp3.

...\top -> sub1 ->
.................sub1-f1.mp3
.................sub1-f2.mp3
..............sub2 ->
.................sub2-f1.mp3
.................sub2-f2.mp3
.............top-f1.mp3
.............top-f2.mp3

In file explorer I shift-drag "top" to desktop; sub1 and sub2 move and an error message appears saying that it can't delete file. I press cancel and upon inspection both sub directories are moved with their files but the files Top-f1.mp3 and Top-f2.mp3 are now gone along with "top" its original location.

Thank you,
john