We found that in upgrading Donna's AI models we had left some "old ways of thinking" in the system. This could lead to Donna getting contradicting opinions about what was and wasn't a date. This meant that sometimes dates would suddenly seem to appear or disappear when updating the document.
We've now resolved the issue. The coming weeks we expect to be deprecating the final parts of the old system which would fully eliminate the possibility of this bug occurring again. But until then, if you run into any funny business...let us know and we'll be able to fix it quickly.