TKEY
The 'Initial key' frame contains the musical key in which the sound starts. It is represented as a string with a maximum length of three characters. The ground keys are represented with "A","B","C","D","E", "F" and "G" and halfkeys represented with "b" and "#". Minor is represented as "m". Example "Cbm". Off key is represented with an "o" only.
Mixxx currently writes the String visible at the GUI into the TKEY field. This is wrong and can cause issues in third party applications.
Bug Description
According to https://id3.org/id3v2.3.0 the content of TKEY is well defined:
Mixxx currently writes the String visible at the GUI into the TKEY field. This is wrong and can cause issues in third party applications.
Version
2.3.3 and main
OS
All