Just a quick confirmation that it’s not working with PHP 7.4, either. My bibliography disappeared after the update. Configuring the bib file in the WordPress menu brought back the bibliography, but grouping and sorting did not work. Rolling back to PHP 7.2 brought back my old bibliography.
Edit: I would suggest documenting dependencies on specific PHP versions, especially since WordPress officially recommends PHP 7.3:
Requirements
Cheers,
Stefan
