Ver 4.18.1 Cannot Change Roles

Were those roles created by some plugin? What plugin? Some plugins, like bbPress, create roles on the fly for every page request. There is no sense to modify them with User Role Editor, as URE uses the WordPress core API to save changes to the database, but plugin modifies roles after they were loaded from the DB.

One other rare but still possible reason: Check if your site uses any caching technology, like Varnish or Memcached. Try to turn them off temporarily. If that will help, try to set up the exclusion for URE page, or make changes to the roles with caching deactivated.