Four of the stairs in Andothren are so steep to climb - you simply fall back to the base. In all cases, it is due to meshes that have been merged into Tamriel_Data (some of them likely in the addon). For T_De_SetHla_X_Ando_B_10, two of the staircases are problematic (have a look at the building placed in Andothren, Docks), whereas for T_De_SetHla_X_Ando_B_09 and T_De_SetHla_X_Balcony_09 it is only one of them.