Place onion inside chicken cavity; tie legs with cooking twine. Pat chicken dry with paper towels. In small bowl, mix melted butter, thyme, salt, paprika and pepper; brush on chicken. Place chicken breast side up on rack. Secure lid; set pressure valve to SEALING. Select MANUAL; cook on high pressure 27 minutes. Select CANCEL. Keep pressure valve in SEALING position to release pressure naturally. Internal temperature in thigh should be at least 165°F using instant-read thermometer. If chicken is not done, select MANUAL and cook on high pressure 2 to 5 minutes longer. Select CANCEL. Keep pressure valve in SEALING position to release pressure naturally.