pmartin172 I think you may be misinterpreting the price threshold in the Advanced settings.
It's there mainly for plunge pricing, to enable people to not miss out on really cheap slots (even outside agile charge windows).
So in your case of 3p, you are effectively saying "select any price under 3p, regardless of my agile charge window settings".
As there are no slots under 3p, no prices under 3p/kwH are selected.
The default is to select the cheapest number of slots for your Agile charge window.
Hope that makes sense.