Unwanted split / renaming of the title-filename that also forces folder creation and file movement

I think I just won the contest for The Weirdest Mp3tag Bug Ever


To recreate it please:

1] Create a folder named

XYZ

2] Put in it a FLAC file with a TITLE like

1\2

or

1 \ 2

The _FILENAME now is not important as it can be now whatever you like. The important part is the ``````` character, separating at least two other characters. Also the file format is probably irrelevant- I just had to choose one for a purpose of a clearer explanation

3] Now use the "Tag - Filename" icon to copy the data from TITLE to FILENAME

What happened you ask?

I] The FILENAME instead of showing

12.flac

or

1 2.flac

shows respectively

2.flac

or

2.flac

II] A sub-folder was created named

1

III] The file has been placed in that folder. And so the path to it is

...XYZ\1\2.flac

or

...XYZ\1\ 2.flac

IV] Fortunately the TITLE remained intact


And now please, let use continue the exploration of this truly magic bug:

4] Without closing Mp3tag after executing the steps 1-3, rename the TITLE to something like

3/4

[I am using new characters to make it make more clear of what is happening]

5] Use again the "Tag - Filename" icon on the same file to copy the data from TITLE to FILENAME

What happened you ask?

V] The FILENAME instead of showing

34.flac

shows

4.flac

VI] A sub-folder was created [at the same level as the first one] named

3

VII] The file has been placed in that folder. And so the path to it is

...XYX\3\4.flac

VIII] Fortunately the TITLE remained intact

IX] That first sub-folder named

````1```

is now empty

\

You can repeat now that magic trick as many times as you want. But instead of this please:

6] Close Mp3tag and reopen it

7] Load [drop] that file from

...XYX\3\4.flac

8] Execute the steps 4 and 5

\

What happened you ask?
X] The FILENAME instead of showing

34.flac

shows

4.flac

just like before

XI] A sub-folder was created named

3

but within that first sub-folder named

3

XII] The file has been placed in that folder. And so the path for it is

...XYX\3\3\4.flac

as apparently Mp3tag does not remember casting the same spell before a nap

XIII] Fortunately the TITLE remained intact

XIV] That first sub-folder named

3

is now empty- i.e. it does not have a file but it has a sub-folder


This happens in the 2.87 version and must have happened also in earlier versions; and probably happens in the current version. I discovered this by a truly cosmic coincident, when wanting to check something in that only song of mine that has that \ illegal character in a TITLE- and to my disbelief not being able to find it. And that song being absent part is ultra weird and suspicious. Because I would not have deleted this precious to my song purposely and [long story short] I had it in two "versions" [so I had two files with TITLEs that had \]. So this would mean that by accident I must have deleted the exact two files that cause this bug. A 1 in a 10 000 shoot, followed by another 1 in a 10 000 shoot? So a truly 1 in a 1 000 000 shot? Not in my book, not with all of the various fail safes I have in place, which simply multiple those millions. But that is not all

I create backup copies of all of my music. I do not know from when exactly but I have been using TeraCopy [in general and] for this purpose- shortly after I started to use FreeCommander as a sole filehandler, which was around 2014 09 01. So it is pretty much sure that most of my copies after 2014 09 01 were created with it. And by that kind of backup copy I mean a process of coping of all of the folders which are named after a different artist, to a folder names with a date; on a different hard drive. And here are the dates:

2013 09 13

2014 02 01

2014 12 18

2015 04 14

2015 11 02

2016 07 18

2016 09 18

[and 7 further ones]

Why did I list them? Because those \ files have the modified date of 2015 09 21. That parameter [with few exceptions] I keep intact [but I am 100% sure I would have no reason to manipulate it for this particular two files; and also numerous other data indicate to me a lack of such manipulation]. So I should have them backuped onward starting with the copy that is dated as 2015 11 02, right? Well, there are absent almost from any of them. Because from all of my 14 copies only 2 have those files. The 2016 07 18 copy has them in a folder of a completely different artist: in a sub-folder delivered from the TITLE [with the FILENAME having only the part of the TITLE that is after the \]. And the 2014 02 01 copy has those files with a full [thus correct] FILENAME and in a proper sub-folder [correct artist folder]

So the conclusion would be this: my TeraCopy / FreeCommander combo somehow traveled "back in time" those files sometime after 2015 11 02 to a 2014 02 01 backup folder; while my Mp3tag around 2016 07 18 somehow expanded the bug and additionally moved those files to a folder of a different artist, on top of the normal biding? [That was a question, but this next sentence will be a statement] And something have deleted those files, completely in the original folders [on the main work drive] and in most of the backup copies [on an archival drive]

And I have not checked yet my backup copies on my two off-line drives and on my optical disc- so what kind of magic trickery can I find there?

The \ is a valid character for filenames. It is not an illegal character.
MP3tag has functions to take care of strings before you use them as filenames.
MP3tag is not responsible for the use of its functions or the refusal to do so.