“Invalid index: Cannot index property ’’identifier’’ of type String into type List of Variant

Usually this would mean you're trying to directly reference a property (in this case named "identifier") of a local variable you expect to be loaded with a CDT/dictionary containing that property, but in some cases apparently does not contain that (this can result i.e. when a query returns empty).  I don't have any way of making more specific suggestions since you haven't posted any of the code from your rule 'apac_getidentifiersforexcelreport' or told us what it contains, but the first thing you should check for is a place where you're calling i.e. "local!myVariable.identifier", and instead use the property() function to try to access the property in a failsafe manner, i.e. "property(local!myVariable, "identifier", null())"

Usually this would mean you're trying to directly reference a property (in this case named "identifier") of a local variable you expect to be loaded with a CDT/dictionary containing that property, but in some cases apparently does not contain that (this can result i.e. when a query returns empty).  I don't have any way of making more specific suggestions since you haven't posted any of the code from your rule 'apac_getidentifiersforexcelreport' or told us what it contains, but the first thing you should check for is a place where you're calling i.e. "local!myVariable.identifier", and instead use the property() function to try to access the property in a failsafe manner, i.e. "property(local!myVariable, "identifier", null())"

Thanks Mike.
You suggestion worked for me.

Very helpful, thanks!