Thanks, i used your suggestion, except that i selected LP from the Format view instead of selecting Entire Collection. And since i have plenty of LPs that i don't have tracks entered for, i sorted first by duration, then by track count, and selected the LPs with more than one track.

It's not a perfect solution, since the list won't be dynamically updated when i remove a zero-duration LP and replace it with one with track durations, but it will do for now.

Thanks again.