Fill option on GROUP BY has disappeared

I have an Influxdb with grafana, I have some graphs that are working. I have created many of graphs. But now when I try to create a new one, or when I edit and old one. There is no posibiliy to choose “fill” options. Before I could choose betwwen fill (inear), fill (previous), but now I can not choose anything, on “remove” is shown.
If I edit and existing graph; the choose option is shown (e.g. linear) but no other options are shown.

Any hint?

Sorry I was clicking over fill, instead of clicking over NULL.

Please ignore my question.