Tasks triggering tick ISR on dsPIC33CH

Kernel
4

Not really sure, if it is applicable in your case, but you can you try clearing the interrupt early as suggested by @richard-damon in this post:

void __attribute__((__interrupt__, auto_psv)) configTICK_INTERRUPT_HANDLER( void ){
    IFS0bits.T1IF = 0;
	if( xTaskIncrementTick() != pdFALSE ){
		portYIELD();
	}
}

Also, why do you declare vApplicationSetupTickTimerInterrupt as weak?