Queries with hierarchy - spreadsheet results are grouped horizontally rather than listed vertically

I'm experimenting with a query to ensure designers have filled in mandatory model attributes. The idea is to point the query at a group, get a list of models within that group or its subgroups, and identify which ones have left any mandatory attribute blank. So, I designed a simple hierarchical query on group and model

and defined a reasonably straightforward spreadsheet template on Models and their attributes

with Model defined as =QUERY_ITEM("6f0ba47c-97f2-4e2a-be94-b5628c79dc96";TRUE;TRUE) and expected to get a vertical list of models and their attributes. Instead, I get a separate list of repeated Model+attributes columns, apparently one for each level of nesting of Groups (Model (1) next, then Model (2)... and so on depending on nesting depth).

I assume something about the Group hierarchy doesn't play nice with the spreadsheet template, but how? When would I like to repeat objects horizontally, and is there any way of avoiding it?