Unsolved Mystery: Reactions to Post Disappear!

As you know, in the footer to each post, I have included Reactions to the Post via check boxes, like - Is this Post - Knowledge Add, Cool, Stupid. 

Till about 4 pm on July 12, the post titled The Explainer: Foreign Direct Investment had 62 Knowledge Add and 18 Cool reactions (with 0 Stupid). 

Currently, I find that there are only 50 Knowledge Add and 16 Cool; effectively, this means that reactions have disappeared! 

How can this happen? If you can throw some light on this, please post comment.