Create to Final Resolved not working as expected

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Have this column defined as below:

sum( if( inc_performance.intv_type = 4, inc_performance.rel_time ) )

I'm hoping it'll show me the time in seconds associated with an incident from create to final resolved excluding waiting.

Is this accurate? it's just that for a lot of incidents, it's coming over as zero despite there being days between being created and being finally resolved with no waiting status inbetween.