It sounds like the issue here is that you have some values that are quite large, which makes the smaller values (which you're interested in) too small to distinguish from empty values. There are a couple of things you could try to make them more noticeable.
In the Metrics & axes tab, you should find the following options:
Scale type: By setting this to "log", it should make the smaller values more visible. However, a logarithmic scale for the axis may or may not be what you want.
Set axis extents: By setting a custom min/max for the y-axis, you can make the smaller values visible. However, this will make it so any values above the max appear equal.
I hope this helps!