Are you using 2 ossirlatolc? One at the OSCO pin and one at the SOSCO pin? According to the data sheet Timer1 is the SOSCO pin but you also configured a primary external oscillator. Can the primary oscillator be used as the timer or can you use one crystal for all four pins? I’m a little confused about how you set it up. Would the timer still be accurate if you used the internal FRC as the main clock and a crystal for the timer.