I think the model just got tired of reading text and decided to mock us :) Just kidding. The attention mechanism got stuck somehow for this sample. This does not happen very often, though. It's important to note the samples we posted were not cherry-picked: they are just the first 10 sentences from our test set.

Regarding the truncation at the end, that was a bug in our sampling code that we just fixed. We will update the samples soon!