See my reply to this similar question: https://www.researchgate.net/post/The_h_index_remains_unchanged_despite_increasing_citations_number_and_research_score. - Your h-index derived by ResearchGate is already at 59. To reach the next step, 60 of your publications must get at least 60 citations.

William Hall That is a concern. Every so often, the H-index is updated incorrectly because some sites like ORCID and ResearchGate do not auto-update citations unless they come from a closed system like Scopus or Web of Science. Moreover, if your new citations are not accurately connected to your profile, they may be omitted.

Have you gone through verifying the proper indexing of your papers and citations on Google Scholar or Scopus?

This could aid in diagnosing the gap that needs addressing.