I fix it, I just copy the solution from another topic:
When doing the quest to cure merojhed, you have to wait 2 times. When you give the potion to the villagers Melichar allow you to speak with the bandit.
You have to “wait” to see if the cure works on him.
After waiting for a a few jours, u speak with the bandit and do what you want (in my non bugged game, I bring him back to Rattay).
Now you have 2 things to do :.
The merhojed quest ask you to wait more. If you do it, you will be able to speak with Melichar again. He thanks you and give you the villagers reward.
The question and answer quest ask you to speak with radzig. DO IT BEFORE waiting for the merhojed quest.
As soon as u talked to the prisonner, go to the camp for radzig. You’ll wait for the end of merhojed after. Something to try… Worked for several players.