Report Delivery - Agent Completed with Warnings

Summary:

We currently have a report that is scheduled to run daily at around 7am. There are times when the report doesn't send, and it shows the following message below in the snippet. This happens very sporadic; therefore, it is hard to identify a pattern. We have tried to manually run the report to get more detailed info on the warnings, but after running it manually, the agent runs and emails the recipients the report with a status of successful. Does anyone have any thoughts on what may be the cause and how it can be fixed?

Content (required):

FYI- The recipients in this agent are valid email addresses.