So here's my attempt to help you identify the issues with VNAV still. I see there's an experimental download available, but I'm not sure where the "experimental" channel is? Can someone link there?
Airbus: A320 CFM
ERIXU UN860 ETAMO UN855 PPG UP84 ALBER
STAR: ALBER1S into RWY 25L
At CLE there's an altitude restriction on the star that says between 10K and 7K. After passing CLE, the plane did a dive upwards of 7,0