Just kidding, turns out it's a list of tuples

apps/cli/utilities/aat_wrest/aat_wrest/metadata_wrester.py

@@ -436,7 +436,8 @@ class WrestWorkflowMetadata:
                 data = cursor.fetchall()
                 if data:
                     # This should have all the ancillary and science product names
-                    make_json = json.dumps({"filesList": sum(data, [])})
+                    # It returns from the query as a list of tuples, so it must be flattened
+                    make_json = json.dumps({"filesList": list(sum(data, ()))})
                 else:
                     self.logger.error(f"ERROR: Failed to fetch products from product ID {product_group_id}")
             else:

services/workflow/workflow/server.py

@@ -901,3 +901,4 @@ def main(global_config, **settings):
         config.add_tween("workflow.server.prometheus_route_timing_factory")
 
         return config.make_wsgi_app()
+