I have purchased all races, subraces, feats, backgrounds, and spells. In the marketplace it says content unlocked, but while trying to create a new character this morning I noticed the Loxodon wasn't available. Does anybody know what's going on? Or what I did incorrectly?

Check on the first page of the character builder. There is a toggle to allow or not allow MTG content.

Awesome!!! Thank you! I just assumed that since it was from Ravnica I didn't need to check those off.

Ravnica is an MTG setting. Currently GGtR is the only D&D book that is MTG content.