I've noticed similar refusal to auto-generate anything if certain other kinds of words exist in a line.

I'm working on adding some AI text generation into an RPG, trying to liven up the NPCs a little bit. For flavor text, the model gets fed information about the name, race, class and gender of the character they're playing. I've noticed that Copilot will happily autocomplete lines about the character's name and class. But the words 'race' and 'gender' completely halt the auto-completion mechanism. I have to type the entire line out by hand, copilot won't suggest a thing, even when talking about Elves and Orcs. The next line it goes back to normal.

I can't say I'm confused why they did it, though. There's definitely a certain kind of person who would read way too much into whatever hallucinations the model comes up with in those areas.