I apologize for the newbie question, but my mind is still based in Magento 1.9.x, where I'm used to reindexing individual indexes from the Index Management Area.
My question is how do I reindex an individual index? It seems the ability to reindex is no longer available from the management area.
Your indexes will run in the background. You need to have the cron setup to make the indexes work. If you need to run an index manually you can use the CLI .
You can see it here
Use the bin/magento indexer:reindex [indexer] console command, and list the indices to rebuild in place of the [indexer] parameter: https://mage2.pro/t/163