[O] No date/day title in agenda column view

[Gez]

A short while ago I stopped being able to see the names/dates of the
days when viewing the agenda in column view. I can see the overall
title (Week-agenda (W41-W42):) and then the next row displays totalled
effort for the first day in a blue face at the top of the effort
column.  The next rows are the entries for that day, followed by the
totalled effort for the following day, and so on.  The names/dates of
the days are not displayed.  I can't remember if they used to take up
an extra row each or if they were on the same row as the totalled
effort, but either way I can't see them now - perhaps since using my
current version - GNU Emacs 23.3.1 and org-mode version 7.7

My org-columns-default-format is "%1BLOCKED %4TODO %CATEGORY
%5Effort{:} %50ITEM %20TAGS %21ALLTAGS"

Could this be a bug, or have I made this happen with a setting that I
can't remember?

Gez