Are you sure you have MC set to write tags back to your files?
Setting: Tools > Options > General > Importing & Tagging > Update Tags when file info changes
Force tags to be written to individual files on demand: (select some files) > Library Tools > Update Tags (from library)
Brian.
Yes, this tick box is checked.
I also selected one mp3 album in MC and 'updated tags from library', but still I can't see ratings for these songs in MP3Tag, however I can see them in android music app - both before and after updating tags, so tags were written already.
To sum up:
1) MP3 - can't see ratings in MP3Tag, but they are showing correctly in andoid music app
2) M4A - ratings in MP3Tag are shown as 2 times higher than what I have in MC, android music player can't see them
3) FLAC - ratings are shown correctly both in MP3Tag and on Android