FTS trigger works 1 at a time, but fails with bulk insert script

I have set up Postgres FTS on a Django/Python web site, and it works as
expected except for this one thing. When I wrote a script to bulk insert
legacy docs, the script works fine but the FTS trigger does not fire. I
have to go back and open each document one at a time to get them indexed.

What am I missing to make this work? Thanks.

BEGIN
SELECT setweight(to_tsvector(NEW.title), 'A') ||
setweight(to_tsvector(NEW.content), 'B') ||
setweight(to_tsvector(NEW.category), 'D') ||
setweight(to_tsvector(COALESCE(string_agg(tag.tag, ',
'), '')), 'C')
INTO NEW.search_vector
FROM ktab_entry AS entry
LEFT JOIN ktab_entry_tags AS entry_tags ON
entry_tags.entry_id = entry.id
LEFT JOIN ktab_tag AS tag ON tag.id = entry_tags.tag_id
WHERE entry.id = NEW.id
GROUP BY entry.id, category;
RETURN NEW;
END;

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