cimajes

Had the same issue, i fixed it by simply overwriting the facegen created by the CK with the original one. An easier way would be to keep the original mod in a folder, do the nif optimizing, only move the mod.esp to your data folder, open it in CK, save it, move the newly made esp file to your old folder and overwrite. Repack the old folder and install it. It worked with follower mods.