I created a 16 village iron golem farm using village chaining. After saving and reloading the game, once the first autosave occurs, the villages merge into one. The area of the farm is in a ticking area. Included is a zip containing the world prior to the merge. Once the autosave happens, the villages will merge.

It must be noted that I do not think it is happening on autosave. That is just the only time I can view the updated NBT data.

Village data is being saved but it is not loaded.

To reproduce:

Create a village by reproducing the video attached, with the ability to move the villager out of door detection range. Throw snowballs to show angry particle effects. Activate the piston to move the villager out of detection range. Throw snowballs as long as you would like to verify that the village has not been deleted. Save and load the game and then throw snowballs at the villager. No angry particles will be shown.

Separate test:

1. Create a village with 22 doors and 10 villagers.
2. Wait for an iron golem to spawn
3. Punch a villager to anger iron golem
4. Make sure the iron golem doesn't kill you (run into a structure too small for him to enter)
5. Save and quit
6. Log back in. The iron golem won't be angry anymore

Extra: villagers won't run from you for negative attitude points because the old village doesn't exist anymore (their attitude resets to neutral)