Add fundraiser to a List of donors !

@Alejandro Joven
What is your “Filter array” doing?

your expression empty(item()?['fundraiser_id']) is looking at the item in your Apply to each loop, which is a constituent record and looking for a property fundraiser_id inside the constituent record, which doesn't exists, therefore empty() of this property is always going to be TRUE and TRUE = FALSE will also go down the FALSE path of the condition.

List constituent fundraisers action returns a “count” property, which you can use instead in your condition to see if there is any fundraiser or not.

@Alejandro Joven
Then you don't use the “count” property of the list constituent fundraiser action. Your filter will filter the arrray of fundraiser where type=the type you want, so your condition is just going to be using the length() expression to get if length of the filter array action is = 0 or not