Sum of duration in charts

I’m new to the Airtable platform, thank you all for your future answers :slight_smile:
With the Interface Designer application, I would like to display a sum of durations in a graph.
The field is well created as a duration but impossible to sum it in the graphs. On the other hand, no problem in the Number element, the sum of the durations does this well.

Could you help me on this problem where maybe because of BETA version this option is not developed yet?

thank you for your comeback