During the process of upgrading to Sitecore 9.1, I configured Solr indexes, and they show up in dashboard but not showing up in Sitecore indexing manager. Any suggestions/advice?
This can happen if Sitecore can't connect to Solr. Verify that Solr is functional, and connectivity is functional between the Sitecore server and the Solr server.
Also ensure that you have followed the appropriate setup instructions for your version of Sitecore (9.1 linked below):