If you are scanning from the main database, you won't find it in Sentinel, which only deals with Favorites Lists you have created. Not sure if you are scanning the Master HP Database, but this could be a reason.
In any event, when your scanner stops on the "offending" channel, you can simply hit the "Avoid" button. That button is below the display on the left side.
Hitting the Avoid button once does a temporary Avoid (or lockout for us old-timers). Temporary Avoids are released when the scanner is powered down.
Hitting the Avoid button twice in rapid succession does a permanent Avoid. The only way to clear permanent Avoids is through programming on the keypad (or via Sentinel if this is indeed a channel in a Favorites List, but you glanced over it when looking at Sentinel).
