Villagers were changed a lot between 1.14 sub-releases, so it is possible that is fully the "problem" here.
If you update to 1.14.4, you will see that the villagers trade much more, because they did not trade much in 1.14.2 iirc.
Iirc, the movement statistic tracks how far the player has moved, you are looking for the "Distance Walked" and "Distance Sprinted" statistic.
Oh, oops! I completely missed that. I thought I had a better reputation. I think this can be closed. Sorry for wasting anyone's time!
I have experienced this issue in my iron farm, and I found a temporary fix, at least until they actually fix the bug. When I open their GUI, they seem to start again trying to find a bed. Unfortunately, even this does not work all the time. Also, I have seen a video by ilmango that used a trick where he placed a block above their heads to prevent this from happening. The only problem with that fix is that you need to have the block directly above the villager's head, and they sometimes just stand there and spin.
Can you tell us what the actual spot you placed the witch farm at? As in the X and Z of the coordinates. I have a bounding box mod on that can confirm if it is actually the problem.