While building the first hut the progress was only 75% yet a note came up saying the hut had been built and all the villagers celebrated (they eventually completed the hut).

Today, I was able to begin on the last hut and I've had 3/4 builders contructing it. The progress has been unchanged at 1% - just checked and a note came up saying the hut was completed (villagers celebrating again) yet the progress is still at 1%