@salvq There isn’t a way to do this, currently. fill() will replace null values with a specified value, but in your case, there aren’t any points with null values. There just aren’t any points so Flux doesn’t know what to fill.
What Flux is missing is time interpolation – the ability to create points at specific time intervals when no points exists. This is a known issue and there’s an issue/proposal on the Flux repo that outlines the problem and potential solutions: Spec fill/Interpolate function · Issue #436 · influxdata/flux · GitHub
