The system may incur a problem indexing the packets and cause the shaft process to crash or segfault in Security Analytics. Symptoms of a shaft segfault result in reports not completing correctly in the GUI.
The system is built to restart the shaft indexing process if it detects a problem. To test that indexing is happening, you should run any report in Analyze -> Summary. If there are results, then the indexing process is working properly. The most common method to prevent this from an additional occurrences is to upgrade Security Analytics to the latest release. You may also open a case with support for further system review.