STEM OPT extension checklist: E-Verify, the I-983, and reporting

To qualify for the 24-month STEM OPT extension a few things must line up. Your employer must be enrolled in E-Verify. You need a completed Form I-983 training plan tied to your degree. You must report employment and address changes to your DSO, and there are 6-month and 12-month self-evaluations. Missing the reporting is one of the most common avoidable problems. What part of the process tripped you up?