Hi Sami,
I've just encountered a bug when trading using quest payment..
What I've done from start:
I've done quest with branch gathering.
I've been given 5 squirrel hides worth to spend.
I've picked up 14 arrows.
I've started to trade.
Villager said that payment covers nearly half and I have to pay for rest of it.
I've started giving back unpaid arrows to get to the level of 5 squirrel hides.
I've given up 7 arrows and still no satisfaction.
I've given bird skin and I've been told that this is marginal payment for arrows so I've stopped trade.
I've started trade again with 7 unpaid arrows and I've been told that fur hides covers 2/3 of the.
I've given up unpaid arrow and noticed that villager would like me to pay for 6 arrows (it's like quest squirrel hides are not accounted any longer).
I've given up 2 more arrows (leaving me with 4 arrows) and still nothing so I've asked what he wants from me to pay for this trade.
Answer was: "I would like from you." I don't remember exact sentence, but it's the standard one when villager says what he would like from me. (There was nothing he would like from me, just period at the end of sentence). I've stopped trade.
I've started trade again with 4 unpaid arrows and 5 squirrel hides were enough as I get green light on it and traded.
As you can see above, bug probably takes place when you return unpaid item and then script doesn't take quest payment into account in trade.
best regards
nekot..