Hello and thank you for bringing this to the attention of the Community, walleyek! I must admit to a bit of confusion over your experience. One of the benefits of Usage Controls is the ability to block incoming calls. This benefit is controllable by the Account Owner, and should not be subject to a random or scheduled reset. However, there is another feature offered by Verizon Wireless that would reset and allow previously blocked calls to come through. That feature is Call & Message Block. It allows you to add up to five 10 digit phone numbers to each line on your account. The service is free, and resets after 90 days.
Even though the feature resets, you do have the option to return and refresh the feature with the same numbers previously blocked. If you need help determining what your blocking feature allows, please let me know. I'll be happy to review the configuration of your son's line. Thanks again!