See these related discussions:

https://www.researchgate.net/post/Does_anybody_know_how_we_can_add_the_missing_citations_to_our_profile_in_Google_Scholar

https://www.researchgate.net/post/Is_there_any_to_add_the_missing_citations_in_Google_Scholar_Profile

https://www.researchgate.net/post/How-to-add-missing-citations-on-Google-Scholar

https://www.researchgate.net/post/How_can_i_add_missing_citation_to_my_Google_Scholar_profile

https://www.researchgate.net/post/The_article_published_in_a_scientific_journal_within_the_Scopes_container_Why_didnt_a_new_citation_appear_in_Google_Scholar

https://www.researchgate.net/post/Could_you_please_explain_my_inquiry_on_citations

https://www.researchgate.net/post/What_to_do_if_a_citation_is_not_included_in_Google_Scholar

https://www.researchgate.net/post/Why_some_article_citations_is_not_seen_in_the_google_scholar