Query is not returning any value when I am filtered by dropdown value

I have written a query for that I have also define the index  and it is executing correctly but not getting results.

my thought is, property which I am filtering that is set by in aem commerce a dropdown that why it is not able to match but if am filtering a property which set simple text then I am getting results.

for example :

my object look like below:

{
"data": [
[{
"datatype": "DeviceDataUse",
"values": {
"defaultskuid": "141200172",

"identifier": "dvc12080008prd",
"storageunit": "GB",
"availabilitystatus": "Sellable",
"tinynoborder": "xx",
"skuimages": ["xx"]
}
}, {
"datatype": "DeviceSkuDataUse",
"values": {
"halfsize": "xx",
"identifier": "128000055",
"image": ["xx"],
"hexcode": "#1F2120",
"derivedinventorystatus": "BackOrder",
"availabilitystatus": "Supported",
"fullsizeborderlesspng": "xx"
},
"pageUrl": "xx"
}]
]
}

SELECT * FROM [nt:unstructured] AS s WHERE (ISDESCENDANTNODE(s, [/etc/commerce/products/myProject/en/devices])) and s.derivedInventoryStatus = 'BackOrder'

for "identifier" it is working fine.

// queryString = "SELECT * FROM [nt:unstructured] AS s WHERE (ISDESCENDANTNODE(s, [/etc/commerce/products/myProject/en/devices])) and (identifier is not null)";