WTF !

A lot of things changed in Scintilla. I guess that was the reason why I dropped implementing asm folding from v2.27 ...
These are now the options in the properties file for
SciTE:
fold.asm.comment.explicit This option enables folding explicit fold points when using the Asm lexer. Explicit fold points allows adding extra folding by placing a ;{ comment at the start and a ;} at the end of a section that should fold.
fold.asm.comment.multiline Set this property to 1 to enable folding multi-line comments.
fold.asm.explicit.anywhere Set this property to 1 to enable explicit fold points anywhere, not just in line comments.
fold.asm.explicit.end The string to use for explicit fold end points, replacing the standard ;}.
fold.asm.explicit.start The string to use for explicit fold start points, replacing the standard ;{.
fold.asm.syntax.based Set this property to 0 to disable syntax based folding.
However, Notepad++ uses a customized version of Scintilla which uses XML files insted of *.properties files.
Mikl__, it seems you must study the source code of Notepad++ ...
https://github.com/notepad-plus-plus/notepad-plus-plus/blob/master/lexilla/lexers/LexAsm.cxxCode is the same as it is in SciTE. Maybe you should ask the developers of Notepad++ ...