WooCommerce Transients & Orphaned Variations
This is under the WooCommerce Tools tab, this is where we can do some optimising of the underlying database but be careful — don't click anything until you know what it does, there's a couple of dangerous buttons here!
There are only three buttons on this page that we'll be concerned with in this case: Clear transients, Clear expired transients, Clear Orphaned Variations.
We'll start with Clear expired transients. WordPress transients don't always get removed from the database when they expire — they should — but they don't. So, click the Clear expired transients button and WooCommerce will remove any expired transients.
Next, click the Clear transients button. This removes all transients cache data created by WooCommerce used for the products and shop pages.
Lastly Clear Orphaned Variations should never return a value, it is basically cleaning up from some errors but many plugins can create these situations.