I have something that is similar or identical in binary newgroups. I
am adding this comment in hope it adds something. This happened to me
some time ago. If I try to save attachments I get a small .ERRORS
file. I can see the picture just fine in the body pane. If I download
the text I get a .msg file which size varies according to the content.
If I download both text and attachments I get two .ERROR files plus a
.msg file. If I download only the text, I only get a .msg file.
I then can use a program called UUD64Win from http:/www.marks-lab.com
that I point at the .msg file and the picture extracts just fine. I
had not made any changes in my PAN settings, or re-compiled or
whatever. I suspect that M$ Windows 10 had some sort of update that
spoiled things. The .ERROR files have a string such as: "ERROR: Write
error on target file C:\Users\sarah\AppData\Local\Temp\uuH111I1: Bad
file descriptor". There is lots of room on my C: drive.