Hi, I think @Airtoklaus is correct.
For the ID3 format it actually stores separate values using the null character (ascii zero byte) and we can force this using the ‘;;;’, to be clear the ;;; are not actually stored in the file this just indicates that we want to store as multiple values.
Now, this is the official way of storing multiple values in ID3v24, but there is no official support for this in ID3v23, like many applications we do this anyway for ID3v23 but MInimServer will only read multiple values if using ID3v24
Now, we have a option in Preferences called MP3 Metatag Version and you already have this set to V24 so that this will automatically convert V23 to V24 however it only works for Mp3 files not other formats that use ID3 such as Wav, we have an issue for this that I will try and get resolved for next release.
In the meantime the workaround would be to use another tool such as Jaikoz to convert your Wav fields with ID3v23 tags to ID3v24 tags

It has also come to my attention that SongKong does not show the ID3 tag version anywhere so I have raised an issue to address this as well.