My report of the bug was from my single player world after building an iron farm. I haven't gone back to try and recreate as it took ages to get the first two villages over to the farm form the nearest village and, to be honest until the bug is known to be fixed it seems a waste of time and a waste of villagers! I haven't played since the bugged - a slight case of rage quit I fear after spending ages building the farm and transport to it.
I raised a similar problem yesterday and it got closed down and linked to this thread:
"Spent a couple of days, off and on, building an iron farm with a 50 bed villager breeder. Had probably got it up to around 20 villagers and iron has started coming through the collection system. After spending some time repairing tools and levelling at a skeleton spawner XP farm (very close to the iron farm laterally but some way below), I realised that the iron had stopped coming through and after going to investigate, all the villagers had gone. I used one of the more popular designs from youtube and it was working well. The villager area was well lit and had a glass block roof (see attached screenshot). The missing blocks in the shot were taken out after the disappearance. How can I recover the villagers; it took me ages to get the two initial villagers into the farm?"
Been back on to see if I could command in some villagers to my farm, but it appears I didn't turn cheats on for this world. I'm happy to post my world if that helps, but I don't know how to do that.