Dashboard Customize menu does not include the data field

We have run into an issue a couple of times that I think must have an easy solution. I would also assume that we are not the first to see this issue, and be frustrated that there does not seem to be a way to fix it, at least not in the current documentation. We really want to use the native dashboards for internal analysis of raw data, but often end up with the scenario below.

In the “Customize” dropdown menu for dashboards, the choices for the X and Y axis are all time-related. So the data field is not there when this issue occurs. See screenshot below. The self-evident choice of a data column (in the example below, ‘_value’, should be one of the choices, but it is not. I really would like there to be a low-code way of configuring those choices, but it seems like that is not possible.

Any tips or tricks are very welcome! If it turns out to be embarrassingly simple, I will be very happy.