Not sure if my math isn't right but I'm leveling another toon on my box account and my lvl 65 toon isn't getting exp with my other 2 lvl 96. 65x1.5 is 97.5 so I should be ok but it isn't
I'd recommend submitting a ticket to our gms to look into this for you. If there's an issue with the leveling on your character, they may be able to fix it.
This is the correct behavior. level x 1.5 is only correct if the answer is less than or equal to 30. Endiment is correct, 30 levels is the max spread it ever can be.