Ignoring blanks or text in pivot avg calculations

Currently when using the "Within cells list as" average values in a pivot table, the tool seems to treat blanks and text like "N/A" as zeros, which drastically reduces the Avg.

Specific use case for context:

As a product manager, I want to understand my cycle-time for features within my workspace. The only way I can seem to get close is with a pivot report.

In a list report, I created formula fields that calculated the date difference between the dates logged for each status (backlog and grooming, grooming and design, design and develop, etc.). In the formula field, I indicated that if the date is blank to show a blank and not 0. I then bring all of those fields into a pivot view to see the average days, using the average value for "within cells listed as". However, based on the result it looks like those blanks are still treated as zeros.

Your support team suggested to filter out all the blanks, however since filtering the blanks filters the entire feature record, I'm left with a very small sample set (only features that are done and passed through all statuses).

It would be fantastic if you have the avg calculation ignore blanks or offer a different way to calculate feature cycle time within a workspace or release.

Thanks!