Some data points in "Line" visualization cannot draw lines after split series

[grace_Li]

Hello friends,

I'm trying to display some data as a "Line" graph.
The line looks good when not split series.
But I need to split it into 2 lines to compare the trends. After split with a filter, some data points are not able to connected to line:

Anyone knows why and how to fix this please?

[Marta_Bondyra]

Is this Lens? If so, you could change missing values feature, here's before and after example. You can also change the dotted line to a regular one with the setting from the screenshot.