Getting ORA-01779 during update of a table (not a view).

I'm creating what should be a simple merge form.  I query data from one table in the left half of my canvas and I query from a view to on the right side of my canvas.  Once the user has the desired customers in both halves, they click a Merge button to pull ID numbers from the view and update the table with those IDs.

My problem is I'm getting the error ORA-01779: Cannot modify a column which maps to a non key-preserved table during the merge process and no data is updated.

I've researched this error and it consistently relates to updating a view of tables with no primary keys.  The table I'm updating does have a primary key which I'm using in my where clause for the update.  I'm at a loss since my update is on a lone table with a primary key.  Is there some actitivity going on behind the scenes with the view I'm using.  The view doesn't include the table that I'm updating.