Importing ffmetadata file into MP4 supports chapters but ignores global tags

[LigH]

Summary of the bug:

I can add an ffmetadata file to an MP4 file to include movie chapters. But global tags for the whole movie, like title and comment, in the same file are not added.

How to reproduce:

(Windows 10 64bit)

qaac64 -V 64 -q 1 -o PAL.m4a PAL.avs
x264 --crf 25 --preset slow --nr 500 --colormatrix bt709 --transfer bt709 --colorprim bt709 --qpfile PAL.qp -o PAL.v.mp4 PAL.avs
ren PAL.v.mp4 PAL.m4v
ffmpeg -i PAL.m4v -i PAL.m4a -i PAL.ffmetadata -map_metadata 1 -c:v copy -c:a copy -movflags +faststart PAL.mp4

Chapters are read from the file PAL.ffmetadata, successfully inserted in the MP4 file, media players can handle the chapters (the "Menu" entry is reported even twice - is that necessary at all?), but global tags "title" and "comment" in the same file are ignored.

Sample files and some console outputs (analysis logs by "MediaInfo -f" and "MP4Box -infox") are attached in a ZIP archive.

[LigH]

Is it even supposed to work this way? Documentation about ffmetadata files is sparse.

[LigH]

It works with -map_metadata 2. I wish this was documented.