See attached mapping date, replacing original value "TRUE" with value "1", but ca_objects_deaccession.is_deaccessioned is not getting set.
The target in your mapping is off. It needs to be ca_objects.is_deaccessioned rather than ca_objects_deaccession.is_deaccessioned. The "is_deaccessioned" field is part of the ca_objects record. Corrected mapping is attached.
Ahh ok. I need to update the Wiki page on this as it's misleading. It cites the sub-elements for "ca_objects_deaccession" as
The editor UI bundle for the deaccession ensemble is ca_objects_deaccession. The fields are just plain old fields in the ca_objects table, so they all need "ca_objects." as a prefix