There is no support for CUE in tagcache database AFAIK, if you use FLAC with CUE. It shows <Untagged> for my APE+CUE as well. This is a shortcoming of current cuesheet and tagcache implementation. It would be nice to add data from cue sheet into database by treating APE/FLAC/WV as a yet another folder and, for non-existent files, check existence of a file before the last separator ('/'). It should not be difficult to implement.