We upgraded Plex from version 7.1 to 7.2.1 and found that when we use Qualifier field with a meta cord, there is the field which is not generated by a source code. That is Plex does not generate all qualifier fields for meta query.
CA Plex 7.2.1 and higher
[GeneratorOption]
Traverse All Meta Query Qualifiers=1
The Plex.ini file locates in the Plex install home folder.