Is there a limit to how many IP addresses can be imported in a text file?

I'm running SEP version 12.1.2015. I'm upgrading machines using IP addresses imported from a text file I have created. The most IP addresses I can import at one time is ten. Is this the limit? Is there a way to import more? I have tried text files with 10, 15 and 20 IP addresses. Ten IP addresses work fine. Anymore then 10 IP addresses in the text file and after clicking Import, OK. Nothing shows up in computers.