Found a bug in the filtering algorithm on the 'Select Keyset' screen:

Select 'Make' -> Panasonic
Look at all the 'TV' keysets
Select 'Device' -> TV
Only 'Panasonic TV Keyset 1b' shown

I haven't checked that all other 'Devices' filter out correctly on all 'Makes' but there might be other bugs like that. I think it might even be possible that some keysets are missing if you filter only by 'Make'.