Reference `stocks` was not fetched along with the entity. You need to use `referenceContent` requirement in your `require` part of the query. about evitadb HOT 1 CLOSED

query(
	collection('Product'),
	filterBy(
		and(
			entityLocaleEquals('en'),
			attributeEquals('url', '/en/alcatel-3t-10-2020'),
			priceInPriceLists('basic'),
			priceInCurrency('EUR')
		)
	),
	require(
		entityFetch(
			referenceContentWithAttributes(
				'stocks',
				filterBy(
					attributeGreaterThan('quantityOnStock', 0)
				),
				attributeContent('quantityOnStock'),
				entityFetch(
					attributeContent('name'),
					dataInLocales('en')
				)
			)
		)
	)
)

query(
	collection('Product'),
	filterBy(
		and(
			entityLocaleEquals('en'),
			attributeEquals('url', '/en/alcatel-3t-10-2020'),
			priceInPriceLists('basic'),
			priceInCurrency('EUR')
		)
	),
	require(
		entityFetch(
			referenceContentWithAttributes(
				'stocks',
				attributeContent('quantityOnStock'),
				entityFetch(
					attributeContent('name'),
					dataInLocales('en')
				)
			)
		)
	)
)