Email chain does not show all of the emails

Email chain does not show all of the emails

My inbox is showing the number of emails in an email chain, but it fails to actually produce the emails. See image attached. 

When you click on the number inside the circle, it should show the full email chain, but in this case, only displays the new email and the original one sent-- losing two emails. In fact, those emails aren't anywhere in the inbox and I have to search by the sender to find them. 

(frustrated)

Scott