N1QL: Array Indexing, selecting the element x which is referenced in array index is not covered

create array index:
CREATE INDEX `idxVM2` ON `default`((all (array (`x`.`RAM`) for `x` within `VMs` end)),`VMs`) WITH(

{"index_type" : "memory_optimized"}

)

select query:
explain SELECT x FROM default emp1 USE INDEX(idxVM2) UNNEST emp1.VMs as x JOIN default task ON KEYS meta(`emp1`).id where x.RAM =3 ;

Result:
[
{
"plan": {
"#operator": "Sequence",
"~children": [
{
"#operator": "UnionScan",
"scans": [
{
"#operator": "IndexScan",
"covers": [
"cover ((all (array (`x`.`RAM`) for `x` within (`emp1`.`VMs`) end)))",
"cover ((`emp1`.`VMs`))",
"cover ((meta(`emp1`).`id`))"
],
"index": "idxVM2",
"keyspace": "default",
"namespace": "default",
"spans": [
{
"Range":

{ "High": [ "3" ], "Inclusion": 3, "Low": [ "3" ] }

}
],
"using": "gsi"
}
]
},
{
"#operator": "Parallel",
"~child": {
"#operator": "Sequence",
"~children": [

{ "#operator": "Unnest", "as": "x", "expr": "cover ((`emp1`.`VMs`))" }

,

{ "#operator": "Join", "as": "task", "keyspace": "default", "namespace": "default", "on_keys": "cover ((meta(`emp1`).`id`))" }

,

{ "#operator": "Filter", "condition": "((`x`.`RAM`) = 3)" }

,
{
"#operator": "InitialProject",
"result_terms": [

{ *"expr": "`x`"* }

]
},

{ "#operator": "FinalProject" }

]
}
}
]
},
"text": "SELECT x FROM default emp1 USE INDEX(idxVM2) UNNEST emp1.VMs as x JOIN default task ON KEYS meta(`emp1`).id where x.RAM =3"
}
]

Shouldnt x be covered?