After a 12+ hours of trial and error.
Found the solution to this one.
The solution to the problem is in the description, below...
Using Advanced Custom Fields (ACF) in a custom post. One of the ACF custom fields is
$post_object; and always returns and array of
Under the settings for the custom columns (CAC) set the
Field Type: to
Post Title (Post ID's).
I love love love CAC - I have supported the author monetarily for their efforts.
But please please please provide more documentation, for pete's sake!
It's galling to think how simple the solution was. Went all the way around the block to reach my thumb, as it were.