SSIS dataflow task does not execute, no errors

I've created an SSIS package that contains a dataflow task. When I run the package, the previous 3 tasks complete successfully. Then, the package ends without attempting to execute the dataflow task. There are no errors, and it doesn't appear to try to run the dataflow (no validation of the task, no errors, nothing). There are no conditions other than "success" on the connector between tasks. I can right-click the dataflow and execute it separately, and it validates and executes. If I remove the connector between the third task and the dataflow, dataflow will execute. I've even tried recreating the package, adding tasks and running it. I got to the point where I had my three tasks plus the dataflow all connected and running. I added a task after the dataflow, and then the dataflow stopped executing.