Sensor type/gain not being saved or re-populated properly

gain and some sensor types (trillium compact in this case), do not show in nexus gui when a xml is being re-opened (==fields are not populated in gui). Looking at the xml itself, looks like the sensor type is saved, but somehow doesn't show up (l22 and cmg3t show up in the gui). but I can't find a "gain" field in the xml, is this right?