https://musicbrainz.org/artist/c4da6655-3b40-48db-89f5-6841eeb8984e no Wikipedia extract is shown even though a Wikidata link is present.
This seems to happens if
1. there's no wikipedia link on the artist page AND
2. there's a commonswiki sitelink in wikidata (see https://www.wikidata.org/wiki/Q15836534)