Something peculiar in my Topics setup

[hput via "Announcements and discussions for GNUS, the GNU Emacs Usenet newsreader \(in English\)" <info-gnus-english@gnu.org>]

First, I've been using topics in gnus for many years and have not seen
this before.

I have a topic: Watch

Under that topic a number of nnml:directories of certain groups.

One is nnml:all-but-cron_

That group gets copies of all but a select few groups incoming mail.

Sort of a fallback if I lose track of mail in one of the many many
nnml groups.

OK, it nearly always has unread messages.

So one would expect what ever number that is would show up in the
total shown at topic 'watch'. But what I see at topic watch is:

    [ watch -- 0 ]...

No new messages whatsoever.  Not only that but if I do C-u <ret>
telling topic watch to spill its groups, it pops out with:

    [ watch -- 0 ]
      [ banks -- 0 ]
             0: nnml:Chase
             0: nnml:CarringtonBank
             0: nnml:BankOfAmerica
             0: nnml:DSCC
             0: nnml:DSCB
*            0: nnml:synchronyBankAlerts
*            0: nnml:Golden1

But if I press 'j' and give the groupname: nnml:all-but-cron_

Look what happens:

    [ watch -- 0 ]
         235: nnml:all-but-cron_
      [ banks -- 0 ]
             0: nnml:Chase
             0: nnml:CarringtonBank
             0: nnml:BankOfAmerica
             0: nnml:DSCC
             0: nnml:DSCB
*            0: nnml:synchronyBankAlerts
*            0: nnml:Golden1

It was there under watch all along... and with unread messages which
should have shown at `watch'

and C-u <RET> on watch should have dumped it into sight.

So the topic watch neither registers the unread messaages in
nnml:all-but-cron_

Nor displays nnml:all-but-cron_ when asked with C-u <RET> on `watch'.

futher there are others with unread messages under there too:

`J' nnml:inco <ret>  and see what we get:

    [ watch -- 0 ]
         256: nnml:inco
         235: nnml:all-but-cron_
      [ banks -- 0 ]
             0: nnml:Chase
             0: nnml:CarringtonBank
             0: nnml:BankOfAmerica
             0: nnml:DSCC
             0: nnml:DSCB
*            0: nnml:synchronyBankAlerts
*            0: nnml:Golden1

nnml:inco comes out from under `watch' also with unread messages.

This is all wrong wrong wrong... and I've never noticed something like
it to happen.

Can anyone offer a guess as to what is causing "topic modes'" misbehavior?