About certain msgs not downloading with agent

[Harry Putnam]

Running
  emacs GNU Emacs 26.0.50.1 (x86_64-unknown-linux-gnu, X toolkit,
   Xaw3d scroll bars) of 2017-01-01

 Gnus v5.13

I've been downloading very old and up to present posts in certain
newsgroups.

I've noticed there are certain posts that will not download.

What seems peculiar is that I can open and read them so its clear they
are on the pool and not expired or canceled or the like.

Still all efforts of marking with (%) and then with #, then calling
`J s' which is supposed to download a marked message.

And: That process has downloaded many thousands of messages since I started
this project, but will not get certain msgs.

The most recent two I've hit are:

  From: Alexander Dalloz <alexander.dalloz@uni-bielefeld.de>
  Subject: Re: smtp auth redhat9 problem
  Newsgroups: comp.mail.sendmail
  Date: Sun, 20 Jul 2003 20:45:04 +0200 (13 years, 44 weeks, 10 hours ago)
  Message-ID: <bfenu3$dm5t8$1@ID-2108.news.uni-berlin.de>

and

  From: "Frank Apap" <gunygoogoo@yahoo.com>
  Subject: Mail Send FROM names
  Newsgroups: comp.mail.sendmail
  Date: Sun, 20 Jul 2003 20:51:08 GMT (13 years, 44 weeks, 8 hours ago)
  Message-ID: <0hDSa.30730$ye5.7140375@news4.srv.hcvlny.cv.net>

Note the dates

I can see and read the full msg... but they will not download.
And yes, I am in `plugged' mode.

Can anyone take and informed guess as to why this is so?