Adding the Magus Arcana "Spell Blending", and then choosing a Wizard spell (such as "Mage Armor") does not add the selected spell to the available spells under the Spell Tab.
Steps to Recreate:
Create a magus character
Level up to Magus(3)
Add "Spell Blending" as the magus' arcana
Add "Mage Armor" to the spell blending choice from the Lvl1 selection list
Go to Spells Tab
Search for Mage Armor under Known Spells subtab
I've also attached a character that shows this behavior.