I've found the same issue - and I've discovered it's because of the pen. The pen they give to you by default writes poorly once your notebook has been used up. The clickable one and skinny ones are fine and write like day 1.

https://www.walmart.com/ip/Pilot-Frixion-Clicker-Erasable-Ge...

https://www.walmart.com/ip/Pilot-FriXion-ColorSticks-Erasabl...