https://forums.totalwar.org/vb/showthread.php?t=94042

"There appears to be a bug, a mismatch between EDU and EDB. EDB says you should only be able to recruit untowered elephants, while EDU says you should be able to recruit any elephant but the untowered ones. I suggest you add the numidia ownership to the forest elephants in EDU..." "...What you do is open EB/Data/export_descr_unit.txt (hence EDU), then search out the african forest elephants, and add numidia among the owners of the unit."