Players have encountered a glitch in The Witcher 3: Wild Hunt that's preventing them from earning experience points from certain quests. CD Projekt RED says it will resolve the issue "as soon as possible across all platforms (Monday for PC & patch 1.04 on consoles in the following days)."
According to community and website coordinator Marcin Momot, the bug "doesn't impact the game balance in any significant way ... you will be able to finish the game with your character achieving a level within the threshold we had in mind when we designed the game."
Still, just knowing the issue exists is discouraging regardless of how large or small an impact it actually has. It's worth mentioning that the patch won't add back any lost XP once it goes live.