On closer examination of the reason why images in e-mails from senders
that I had entered in a second(ary) addressbook under 1.0.7 were not
displayed in 1.5, I found that the second(ary) addressbook was present
in 1.5, but it was empty.

Simply copying a backup version of abook-1.mab resolved the problem.

Is this a known issue?

Or perhaps it was somehow related to my (now resolved) settings problem?

Herbert Eppel