Measures Project Overview for entire project

So can you help explain how the “measures” tab determines it’s numbers because the values are confusing. I did a fresh build of our latest release branch and I saw the branch shows up in SonarQube as a long-lived branch now. so I switch to that branch and click on the “measures” tab. The Project Overview bubble graph shows 500 / 1421 files. But when I expand the “Size” metric, it shows 1178 files. 1421 != 1178, so why the difference? Furthermore, from the source code I know there are 1048 Java source files in the project. However in SonarQube, if drill into the “Size” > Files metric and count the number of Java files that count is only 805. So it seems line SonarQube is missing over 200 Java source files?