High chances of the situation that in your data model some of the dimensions are not associated as needed and causing cross join but cannot be 100% sure without seeing data model and the chart dimensions/measures.
try not using getfieldselection() function. Pick(Match()) is also preferred over If() in most cases.Try Using that too.
In QS unfortunately this feature of hiding the measure isnt available yet, there are few extensions available.try using them instead.
Post the qvf that you have problem with, in a table,the engine calculates for each and every row/column but not in a KPI where you have a single value aggregated over a set of data,so obviously there would be a latency,so we have to recheck the conditions.
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