video – FFmpeg does not encode chapter titles

I am trying to add chapters to a .mp4 file.
When I tried extracting the metadata using the following command:

ffmpeg -i INPUT.mp4 -f ffmetadata FFMETADATAFILE.txt

I got an output file as follows:

;FFMETADATA1
major_brand=mp42
minor_version=0
compatible_brands=isommp42
encoder=Lavf60.15.100

So now I try to add some chapters as such

[CHAPTER]
TIMEBASE=1/1000
START=0
END=424510
title=mytitle1

[CHAPTER]
TIMEBASE=1/1000
START=424511
END=941600
title=mytitle2

[CHAPTER]
TIMEBASE=1/1000
START=941601
END=1227260
title=mytitle3

I use the ffmpeg -i INPUT.mp4 -i FFMETADATAFILE.txt -map_metadata 1 -codec copy OUTPUT.mp4 command to encode the metadata to my video file, and for some reason I only ever get ‘Chapter 0’, ‘Chapter 1’, and ‘Chapter 2’.

I tried using the -map_chapters 1 argument as well but results have been unchanged.

I am using the Latest Auto-Build (2023-10-14 13:02) Windows build by BtbN. Thanks in advance for the help.