EXP Book Bonus Not Applied After Mission (Level 25 Reverts to 24)

I used one of the EXP books "the long way home" and equipped it during the same run. Inside the mission I reached level 25, but when I left the mission I was back to level 24. In the mission report, it shows that I reached level 25, and in the EXP details it shows the extra %115 EXP from the books. However, it seems like that bonus EXP isn't actually being applied to my real character level. It's as if the bonus appears in the report but doesn't count toward my actual level progression. im using the long way home, how to specialize in combat and wifflebat for beginners books