This is the first time I'm having an issue with this perk. It still activates and makes the noise, but I no longer see the increase in EXP from either a kill, quest, action, etc. The first time this problem came about was after sleeping and getting the "well-rested" bonus. So far, I haven't seen it return to normal. Not sure if anyone else has experienced this yet or not, but I have the perk maxed out which makes it kind of a slap in the face.

EDIT: After further investigation, it appears that my EXP gain is glitched altogether. No matter the difficulty I'm at, the EXP gain remains the same. So there is definitely something odd happening. It also appears to fix itself (slightly) if I'm sneaking. But otherwise the stock values do not change no matter what difficulty I'm on. Weird.

I have this problem too. it started recently happening. Have you found the intelligence boblehead? im wondering if it bugs the perk

I don't think it's related quite honestly but it could be different for everyone. For myself it was working with 10 Intelligence on the third tier for this perk. I first noticed this problem when attempting to do the Learning Curve quest. Halfway through the quest I rested in a bed and then I had the well-rested bonus activate. I'm wondering if it has to do with that but I am not sure. I rarely rest so it could be the cause. So after I rested, my EXP gain became locked as in no matter the difficulty I was set to, it didn't change the amount of EXP I gained. It seems to be stuck on Very Easy EXP gain even though I play on Normal. I did change it to Very Easy before I rested though. Hopefully it fixes itself or fixed by Bethesda.