@Chris,
I noticed that you said you're on AMP version 7.5.1, is that a typo? Current release is 7.6.1. Please verify by checking:
# root; svn info
# amp_version
If you're really on 7.5.1, there were several fixes that were made directly for IAP support in AMP. In the meanwhile, I'll see if there's a lab setup that can replicate what you're seeing.