Ongoing issue since digital conversion. After conversion I scan wth my 622 and usually get 15 channels but am missing sub channels 57.1 and 57.2. If I do another scan I get 57.1 and 57.2 but lose 33.2- 33.3 and 33.4. If I continue to rescan it just alternates between getting the 57s or the 33s. Signal strength is good on all channels. Any thoughts.