shadows follow very strict rules in order to work besides being closed/triangulated/hard edged:

• the only SV lods the game acknowledges are either 0 or 10 (1000 and 1010 are reserved and usually added automatically by the tools upon binarization)
• the named property 'lodnoshadow = 1' intuitively disables the shadows if its present in shadowvolume LODs

all models need to be refactored and made sure that the SV lod is set to 0, and that there are no named properties in said LOD.