I had this problem today and I managed to actually solve it! They were a little bit far from the village so I had to use minecarts to move them back into the village. then I broke all beds in the village (most of them actually) and broke some of the profession blocks then I placed them again next to each other inside the village. The villagers occupied the new beds and profession blocks. I left them for 1 or 2 in game days and finally I am able to trade with them without the GUI closing.
Omar Abdelkareem
I had this problem today and I managed to actually solve it! They were a little bit far from the village so I had to use minecarts to move them back into the village. then I broke all beds in the village (most of them actually) and broke some of the profession blocks then I placed them again next to each other inside the village. The villagers occupied the new beds and profession blocks. I left them for 1 or 2 in game days and finally I am able to trade with them without the GUI closing.