@willrnt To find the first non-null value, you will need to use a Group By tile instead of the formula tile since you want to look across multiple rows. You should be able to select first non-null value in the aggregation type drop down. Coalesce looks across multiple columns within the same row.

@willrnt Try adding a constant value in the before your Group By tile and use that as your only group by column. Since the entire field is a constant, then it will return a single value as the first non-null value in your dataset.