Redo the multi-dev site index following step 5: https://pantheon.io/docs/wordpress-solr
Index all publicly queryable post types by navigating to the Actions tab and clicking Start Index next to Index Searchable Post Types, or via Terminus:
terminus wp <site>.<env> -- solr indexe.g.
terminus wp cornell-alumni.pr-214 -- solr index
Re-index live site
terminus wp cornell-alumni.live -- solr index