Using parameters reduces my sample quantity

Hello, I hope you are well. 

I have a data source with 70 numerical values (satisfaction score, # tickets, # logins, etc), I am trying to create a scatter plot where I can choose within these 70 values to each one as x or y axis, so that whoever wants can check if there is any kind of relation. The problem I have is that when using parameters, as I add values that have null values in their data, the sample gets smaller and smaller. I understand that if I am analyzing those values it happens, but when I compare values that do not have null values, they are still reduced.

To create the scatter plot, I followed this video -> https://youtu.be/W4ZFlRtcEq8

I would be very grateful if someone can guide me so that this does not happen.