Can't draw automation in Cubase 9.5


Sometimes when I try to draw automation in with my pencil (especially a single point of automation), the automation point/s disappear/s as soon as I let go of the mouse button.

In order to draw in the automation, I have to draw a whole lot of random points in one go, and then sometimes some of them stick, and I can delete what I don’t want and move what I do want to the correct position. But working like this is tedious for something as simple as adding one point of automation in a particular place.

I don’t have snap activated.

Is there a reason that anyone knows of why this happens, and how I can avoid it please?

Thank you for your time and help.