Dynamic inventory shows some internal host incorrectly

I am currently using dynamic inventory with ec2.ini set to use private_dns_name & private_ip_address

However certain host in a different subnet are showing up as ip-x.x.x.x.ec2-internal as opposed to just returning their private IP (which they have). Does anyone have an idea why this is happening?

e.g. I ran a plugin across the host based on tag and some returned incorrectly:

https://lh3.googleusercontent.com/-OmqJniJvG7Y/WUgN-qHyucI/AAAAAAAAF70/f0v4VxQah7srqLTtFKjHL4Z-joQ7sSbhwCLcBGAs/s1600/Selection_019.png