Villagers’ trading screen will not allow the player to stack similar items when double clicking.
Environment
-spawn a villager or wandering trader and enter their UI
-separate two stackable items into different slots
-attempt to double left-click one of them and notice they will not stack together like it should in the inventory or other item UI.
Thank you for your report!
We're tracking this issue in MC-148867, so this ticket is being resolved and linked as a duplicate.
That ticket has already been resolved as working as intended, which means this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.
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 (Technical Issues) – 📧 Microsoft Support (Account Issues)
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki