Index has 0 entries when NESTED ARRAY FLATTEN_KEYS() and one of them has MISSING

UPSERT INTO default VALUES("k03", { "a": [ { "id": "1" },

                                           { "a1": [

                                  { "ch": { "name": "phoneNumber", "value": { "value": "111111111" }}, "type": "Phone" },

                                  { "ch": { "name": "email", "value": { "value": "abc@gmail.com" }}, "type": "email" } ] } ] });

CREATE INDEX ix21 ON default( DISTINCT ARRAY ( DISTINCT ARRAY FLATTEN_KEYS(c.ch.`value`.`value`, c.type) FOR c IN r.a1 END) FOR r IN a END);

SELECT d.*

FROM default AS d

WHERE ANY r IN a SATISFIES ANY c IN r.a1 SATISFIES c.ch.`value`.`value` = "111111111" AND c.type = "Phone" END END;

cbindex -auth Administrator:password -type=scanAll -bucket default -index ix21

ScanAll index:

Total number of entries:  0