Why was my son's online 90-day address notification rejected without explanation?

The poster's son faced an issue where his online submission for the 90-day address notification was rejected without any explanation, despite being submitted before the deadline. Several commenters mention that there is a reprieve from the 90-day reporting until July 31 due to the visa amnesty, suggesting that there should not be a queue at the immigration office. Some provide insights about proper submission timing for online notifications, indicating that they need to be done between 15 to 7 days prior to the deadline. The overall sentiment suggests confusion and concern over the process and the unexpected rejection.