I don't actually know exactly how to set these, but I have tried a few combinations to try and make it work.
I thought that setting Read: to ID3v2.3 and APE and Write: to ID3v2.3 and APEv2 would work.
When I do this, it allows me to see and edit the APE tag.
But then I run this Action: Remove fields: "REPLAYGAIN_ALBUM_GAIN; REPLAYGAIN_ALBUM_PEAK; REPLAYGAIN_TRACK_GAIN; REPLAYGAIN_TRACK_PEAK", it does what I want to the APE tag, but wipes all of my ID3 tags clean.
I want to preserve all the info in the ID3 tags and remove those four fields in the first post
But you can write TXXX frames in ID3v2 tags. You can, for instance, manually write a TXXX/MP3GAIN_ALBUM_MINMAX field in an ID3v2 tag. So is there some way to copy an APE field to a TXXX frame of the same name? I'm guessing that the genuinely oddball implementation of the read/write settings for different types of tags in Mp3 files precludes doing this.