Just ran into this issue with a well developed village (1.14.4). I had several farmers leveled to master, moved a bunch of compost bins to make space for new planting, and then couldn't open the trade GUI with anyone save the newest (untraded) farmers.
I found a workaround to this problem. I moved the master farmers to a villager trading area (about 80 blocks away) and gave them their own work station (compost bin). This worked repeatedly (about 7 or 8 farmers). They retained their trades and discounts.
Had 3 name tagged (in boats) zombies despawn on me one after the other in 1.14.3. I use these for a variety of reasons. Other than naming nothing changed on these entities
Just ran into this issue with a well developed village (1.14.4). I had several farmers leveled to master, moved a bunch of compost bins to make space for new planting, and then couldn't open the trade GUI with anyone save the newest (untraded) farmers.
I found a workaround to this problem. I moved the master farmers to a villager trading area (about 80 blocks away) and gave them their own work station (compost bin). This worked repeatedly (about 7 or 8 farmers). They retained their trades and discounts.