Hello Ariel, thanks for posting. We have recently decided to deprecate the Rule-Based Scenario Generator due to maintenance issues, and it has been removed from the latest release of InVEST.
If you would like to continue with the Rule-based generator, I’m afraid we don’t have an expert on staff to help anymore. But generally speaking, a KeyError like this one sometimes indicates a value (1.0) that is present in your landcover raster, but not present where it needs to be in one or all of the CSV inputs (or vice versa).