According to ffprobe the tags are just...in different order, and I have no idea how other players deal with that.
EDIT 1: ...Oh, they are also lowercase, maybe that's why.
EDIT 2: Yeah, when I opened libpowerampcore.so in IDA, I noticed that it does `av_dict_get(a1, "R128_TRACK_GAIN", NULL, AV_DICT_MATCH_CASE | AV_DICT_IGNORE_SUFFIX);`, so I assume that if `AV_DICT_MATCH_CASE` was dropped it'd work properly.
EDIT 3: I patched libpowerampcore.so to pass just `AV_DICT_IGNORE_SUFFIX` and that solves the issue ^.^
