I just followed this method to the letter:
https://premium.wpmudev.org/manuals/wpmu-manual-2/creating-a-network-to-enable-wordpress-multisite/ and I'm getting the same issue as I was earlier this year; the subdomain defaults to another site hosted on this same account.
I know Pranaya was able to solve this and I went through the original post. I installed it as the steps he provided but it happened. Then I followed these directions and it happened again.
What on earth am I overlooking? Site looks fine. I create a subdomain site and it goes to another site hosted on my same account.