Crystal Reports not displaying all data

We have a simple report pulling from 3 tables on a sql server. For some reason, data from one table does not fully display. The table is called Referral, and we have some clients that have a Referral record tied to them. Out of a report of 20 records, we will have 3-4 that won't display the referral data (even though I can see it in the database), but the other 16 records will. If I go into the database, and change the data on one of the non-displaying referral records and save, it will start displaying. If I then change the data back to the original, it will also display. Being new to Crystal Reports, I don't know if this is a Crystal issue or a problem at the data source, but thought I would put it out here in case someone is familiar with this problem. Our Crystal Reports version is 2011.

Thanks.