[O] how to debug Archive view in custom agenda

[Ken Mankoff]

when I try to view the Archive (v A) in my custom agenda view, I get an
error: 

Rebuilding agenda buffer...
org-refresh-properties: Wrong type argument: integer-or-marker-p, nil

When I view Archive in the timeline for a single Org file (C-c a L v A)
it works just fine.

How do I debug the above message to determine what might be the cause of
the error?

Thanks,

  -k.