Resolution: Cannot Reproduce
First of all i'm on Xbox one live version v1.2.11
The problem occur on all villagers and was very disapointed.
Also was really appreciated have new items like diamond shovel or any stuff more interesting than a diamond axe with Bane of Arthropods or Silk Touch ... but more like Efficiency Fortune Solidity and for Armorer to sell others diamond armor not only Chestplate
I trade with villagers because my seed not have many diamonds,I play on survival hard mode, so I have made a big farm for win emerald but actually it cost me a lot whereas make me rich and win a lot of emerald. If you sell or buy too much it will block the trade, normally the offer will unlock after few trades but actually not. Depending of type of villagers I have 90% of time 5 or 6 trades lock from one villagers. Normally each trade have a chance of 20% to unlock.
Quote : Trading
"On subsequent trades, it will only have a 20% chance of doing so, per trade. For example, if a farmer villager has a trade which is 8 pumpkins for 1 emerald, and a stack of 64 pumpkins is traded, this will count as 8 attempts with each attempt having a 20% chance to reactivate the villager's trades."
For example for Blacksmith :
One of blacksmiths have a Diamond Pickaxe Enchanted Silk of Choice.
1. So I buy all diamond pickaxe - Trade Lock (approx 5 6 pickaxe) ; exit ; wait / 84 emerald lost
2. I sell all charcoal - Trade Lock ; exit ; wait / 20 emerald win
3. I buy all Iron Pickaxe - Trade Lock (approx 5 6) ; exit ; wait - 50 emerald lost
4. I buy all Iron Shovel - Trade Lock (approx 5 6) ; exit ; wait - 50 emerald lost
5. I need to sell iron for unlock all trade !!! - 10 emerald but loosing iron ...
Example of Farmer :
1. Sell all Wheat - Trade Lock ; exit ; wait
2. Sell all Potatoes - Trade Lock ; exit ; wait
3. Sell all Carrot - Trade Lock ; exit ; wait
4. Sell all Pumpkin - Trade Lock ; exit ; wait
5. Sell all Melon - Trade Lock ; exit ; wait
6. Buy all Apple - Trade Lock ; exit ; wait
7. Buy some bread - Woohoo unlock all !!!
As I said up, my seed not have so much diamonds on it and the only way for me to have diamond tools is to buy it. I play with friends actually 3 on survival hard mode. Actually was very disapointed because each time we want to buy tools lock happen and cost really much for unlock in emerald. And farmer are lock constantly because of selling to small quantity.
Just make it playable as we don't need to loose more emerald than the gain of work with diamonds tools.
Sorry for my english, but I'm not native.