When 'Artist' (or I suspect any tag) includes a character like '/' AND you are using path separators ('') in the format string the output filename will get scrambled.
Example
Artist: LSO / Sir Colin Davis
Format string: m:\%artist%\%album%$num(%track%,2) - %title%
Will create (preview windows):
"F:\Audio\downloads\0702tr-LSO-Colin-Davis-Haydn-Symphonies-92-and-93-FLAC16\0702tr-LSO-Colin-Davis-Haydn-Symphonies-92-and-93-FLAC 16\01. HAYDN Symphony No 92 01 Adagio - Allegro spiritoso.flac" ->
"F:\Audio\downloads\m\LSO Sir Colin Davis\HAYDN Symphonies Nos 92 & 93\01 - 1. HAYDN Symphony No 92 i Adagio - Allegro spiritoso.flac"
instead of the expected:
"m:\LSO Sir Colin Davis\HAYDN Symphonies Nos 92 & 93\01 - 1. HAYDN Symphony No 92 i Adagio - Allegro spiritoso.flac"
Note: this will possible be an issue with oither escape charavcters as well ( ';"{ ) togh I have not tested this.
There is a problem with the forbidden slash character "/" within the assembled filepathname.
You can try this ...
With ARTIST ='LSO / Sir Colin Davis'...$validate('m:\'%ARTIST%'\'%ALBUM%'\'$num(%TRACK%,2)' - '%TITLE%,'_')==>'m:\LSO _ Sir Colin Davis\...'$validate('m:\'%ARTIST%'\'%ALBUM%'\'$num(%TRACK%,2)' - '%TITLE%,)==>'m:\LSO Sir Colin Davis\...'$replace('m:\'%ARTIST%'\'%ALBUM%'\'$num(%TRACK%,2)' - '%TITLE%,' / ','')==>'m:\LSO Sir Colin Davis\...'
If you don't want to rely on the Mp3tag function $validate(), ...
then you may apply your own function ...
$regexp(your_filename_ext,'[\x3A\x2A\x3F\x5C\x2F\x22\x3C\x3E\x7C\0-\x1F]','_')$regexp(your_folderpath,'[\x22\x3C\x3E\x7C\0-\x1F]','_')... or ... including slash character / ...$regexp(your_folderpath,'[\x2F\x22\x3C\x3E\x7C\0-\x1F]','_')