The farmer villager oddly speaking, does not want to trade the pumpkins even though it shows that the the deal is available. In the image, you can see I offered more than the amount of pumpkins for an emerald, however when I attempt to put it in the right slot, the emerald icon to complete the trade does not appear. Though not tested yet, I am pretty sure this is the same case with melon blocks.
Thank you for your report!
We're tracking this issue in MCPE-105540, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
-- I am a bot. This action was performed automatically! Please report any issues on Discord or Reddit