Importing large numbers is breaking the import

Hi and thanks. ??

I have to import every single city/state relationship into my database – when I upload 5-10 of them, it works properly, so the syntax is correct. When I upload 100? It still works. When I upload 150? It is dying – the import itself works, but the drop down when editing is no longer dropping down, indicating that the import has been corrupted somehow.

Can you have a look at this? I would be thrilled to share screen and show you exactly what I mean. THANKS!

Steve