Your drop down box for Team1-3 and for Team2-3 are not set to use the filter owssvr data source for their entries - is that intentional? Your drop down list boxes are conditionally formatted - any chance that you are looking at the ones that don't use the data source and have no entries hard coded?
Also, can you drag the z:row node from you FilterOwssvr data source onto your form while you preview it - see if the actual available values in your data source are changing? I see no logic that should cause those to change unless the Sport is changed.