Complex sentence: This material remained on the shelf until 1990, damaging Eight Seconds' significant momentum, and that, combined with the dissolution of their U.S. record label ATCO, led to the band breaking up shortly afterward.
Split into simpler sentences: This material remained on the shelf until 1990, damaging Eight Seconds' significant momentum. This, combined with the dissolution of their U.S. record label ATCO, led to the band breaking up shortly afterward.