Disjunctive filter in SPARQL query

Question

I want to search a case law database for a specific title. I look for that title in the ?title and ?alttitle properties, using FILTER and || (logical-or).

Now I have noticed that this only seems to yield results when both FILTER conditions are true. So, the example below yields no results, even though the value of the ?alttitle field in the record I'm looking for is "NTN Toyo Bearing and Others v Council" and the value of the ?title field is "NTN Toyo Bearing Company Ltd and others v Council". I would expect the fact that there is a match in the ?alttitle property to be sufficient when using ||.

How can I make sure that this record is returned even if there is only a match with the ?alttitle value? Additionally, any tips to make this query faster are appreciated.

SPARQL Endpoint: http://publications.europa.eu/webapi/rdf/sparql

PREFIX cdm: <http://publications.europa.eu/ontology/cdm#>
SELECT DISTINCT ?work ?expression ?ecli ?celex ?alttitle ?agname ?title
WHERE {{{
?work a ?class.
?expression cdm:expression_belongs_to_work ?work.
?expression cdm:expression_title ?title.
?expression cdm:expression_uses_language <http://publications.europa.eu/resource/authority/language/ENG>.
?work cdm:case-law_ecli ?ecli.
?work cdm:resource_legal_id_celex ?celex.

OPTIONAL{?expression cdm:expression_case-law_parties|cdm:expression_title_alternative ?alttitle}
}

                  
FILTER(?class in (<http://publications.europa.eu/ontology/cdm#judgement>,<http://publications.europa.eu/ontology/cdm#opinion_cjeu>))
FILTER (CONTAINS(?alttitle, "NTN Toyo Bearing and Others v Council")||CONTAINS(?title,"NTN Toyo Bearing v Council"))}

UNION{?work a ?class.
?expression cdm:expression_belongs_to_work ?work.
?expression cdm:expression_title ?title.
?expression cdm:expression_uses_language <http://publications.europa.eu/resource/authority/language/ENG>.
?work cdm:case-law_ecli ?ecli.
?work cdm:resource_legal_id_celex ?celex.
?work cdm:case-law_delivered_by_advocate-general ?ag.
?ag cdm:agent_name ?agname.

OPTIONAL{?expression cdm:expression_case-law_parties|cdm:expression_title_alternative ?alttitle}

         }
FILTER(?class in (<http://publications.europa.eu/ontology/cdm#opinion_advocate-general>))
FILTER (CONTAINS(?alttitle, "NTN Toyo Bearing and Others v Council")||CONTAINS(?title,"NTN Toyo Bearing v Council"))}

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