I have provided an answer where I fail to find a critical source. After looking for it again today, I still cannot find it. Worse still, I have read new articles, reviewed some at the time, and cannot find any other report that explicitly shares the critical source's point. I did find reports that elude to the argument.
I have added a warning on that missing source. I believe it does not impact the answer value to the thread, but that missing source does impact credibility. As the accepted answer, I am thinking to delete the paragraph that mentions the source.
What should I do? Leave the warning, remove warning and paragraph?