It returns things like "flow: exports" and "geography: Andorra". Note that clearing all but one facet demonstrates that each works correctly in isolation. It's the combination that's the problem.
This is likely because all dimension-selection criteria are combined with "should" a.k.a OR. Thus we're matching observations where "geography: Germany OR product: Car OR flow: Imports" when we really want "geography: Germany AND product: Car AND flow: Imports" - i.e. "should" over dimensions within a facet and "must" between facets.
This query for the "how many cars do we import from Germany" example should just specify: "geography: Germany, product: Car, flow: Imports".
It returns things like "flow: exports" and "geography: Andorra". Note that clearing all but one facet demonstrates that each works correctly in isolation. It's the combination that's the problem.
This is likely because all dimension-selection criteria are combined with "should" a.k.a OR. Thus we're matching observations where "geography: Germany OR product: Car OR flow: Imports" when we really want "geography: Germany AND product: Car AND flow: Imports" - i.e. "should" over dimensions within a facet and "must" between facets.