Failing to extract image from MP3

I have MP3 files with ID3 images of type "Other". I have tried a variety of methods to extract the images, including the suggestions at https://unix.stackexchange.com/q/41287/34677 To whit:

$ exiftool -a -u -g1 33-Kesh_Jig.mp3
$ ffmpeg -i 33-Kesh_Jig.mp3 qwert.png
$ eyeD3 --write-images=.    33-Kesh_Jig.mp3
$ eyeD3 --write-images=/tmp 33-Kesh_Jig.mp3
$ eyeD3 --write-images=tmp  33-Kesh_Jig.mp3
$ ffmpeg -i 33-Kesh_Jig.mp3 -an -c:v copy file.jpg
$ ffmpeg -i 33-Kesh_Jig.mp3 -an -c:v copy file.png
$ exiftool -a -G4 "-picture*" 33-Kesh_Jig.mp3
$ exiftool -picture -b 33-Kesh_Jig.mp3 > other.png
$ eog other.png
$ most other.png
$ exiftool -W %d%f_%t%-c.%s -b -preview:all DIR
$ exiftool -W %d%f_%t%-c.%s -b -preview:all /tmp
$ exiftool -W %d%f_%t%-c.%s -b -preview:all /tmp 33-Kesh_Jig.mp3
$ most 33-Kesh_Jig_Picture.dat

(most is simply a pager that automatically detects binary data and displays it in a hex dump format.) Either I get no file at all, or I get a file which contains IHDR and Adobe XMP text strngs in it. When the file is played with VLC, the image shows up correctly. So it does not appear to be corrupt. ffprobe has an error Unknown attached picture mimetype: , skipping. but exiftool -a -u -g1 33-Kesh_Jig.mp3 reports:

Picture MIME Type    :
Picture Type         : Other
Picture Description  : ‰PNG. .
Picture              : (Binary data 707734 bytes, use -b option to extract)