Complex sentence: In addition, their performances appeared to be lackluster, especially with the latter single, as it was not promoted for a long time period; this may be attributed to the fact that members did not like this album's concept.
Split into simpler sentences: In addition, their performances appeared to be lackluster, especially with the latter single, as it was not promoted for a long time period. This may be attributed to the fact that members did not like this album's concept.