Reply from publisher:
replied 14 days ago
This is rare, but can happen with very large assets. It's not a fault with the asset itself. The good news is it's easy to fix, see my dedicated support page at https://johnleonardfrench.com/support/#unity_import for advice on how to fix it.
If, however, you continue to experience issues let me know and I'll find another way to help you.
All the best,