Variable products seem to be completely broken. I am sometimes able to add some variable products and have them show up on the product page. Usually, not, however. There seems to be very little rhyme or reason for products displaying or not displaying.
I did notice just now (after upgrading to the latest WooCommerce release) that when trying to create the variables (again) I had mistyped and put "16oz" as opposed to "16 oz" (with the space.) Suddenly THAT variation appeared on the front page, but no others. Curious, I went back and removed the spaces for all of them, as follows: 2oz|4.5oz|8oz|16oz The only one to not show up was the 4.5oz entry.
I've seen quite a few other posts regarding this.