Hooray!!

Under FILE -> PREFERENCES , uncheck Use IPP before you compile your plugin

This makes me believe that IPP is not disabled in HISE
'''
clang: error: no such file or directory: '/opt/intel/ipp/lib/libippi.a'

clang: error: no such file or directory: '/opt/intel/ipp/lib/libipps.a'

clang: error: no such file or directory: '/opt/intel/ipp/lib/libippvm.a'

clang: error: no such file or directory: '/opt/intel/ipp/lib/libippcore.a'

@remarkablex excellent info!

Have you tried compiling the latest version of HISE? We're well past 1.0

Manually coding the outputs didn't change a thing. The solution was to put each sampler into it's own container, and then assign those containers to the appropriate outputs. There's still something fishy going on with the routing though... Samplers can only be assigned to different outputs if the number of outputs from the container match the number of outputs in the master container.
For instance:

This will work:

But this will not work:

changing my number of sampler outputs to 16 makes makes the HISE meters return to normal.
Maybe I'll try to manually code the outputs to see what happens.

I'm about to travel down this road as well. Correct me if I'm wrong, but I believe self signing will only allow your plugin to work with a special version of ProTools. For testing purposes only.

@Christoph-Hart Looks like I'm having some issues again with the multichannel plugin version of HISE. It appears that I have my samplers routed properly to the Container's Routing Matrix, and those are assigned to the HISE outputs correctly. It functions properly in HISE, but when I export the VST plug, all samplers default to output 1-2.
What I would expect is:
Sampler 1 output = 1-2
Sampler 2 output = 3-4
Sampler 3 output = 5-6
Sampler 4 output = 7-8
If you look at the Container's Routing Matrix, you can see Outputs 9, 13 and 15 are maxed out even when the samplers are sitting idle.