Imported enum conflict when using Simulink Accelerator

I'm using various enumerations in Simulink that are defined externally in a C header file.

For Simulink to use and understand the enumerated data type, I follow these instructions: Import Enumerations Defined Externally to MATLAB.

Below you can see an example of an enumeration:

classdef(Enumeration) BasicColors < Simulink.IntEnumType
    enumeration
        Red(0)
        Yellow(1)
        Blue(2)
    end
    methods (Static = true)
        function retVal = getHeaderFile()
            retVal = 'enum_list.h';
        end
        function retVal = getDataScope()
            retVal = 'Imported';
        end
    end
end

This works very well for Normal simulation and code generation. However when I try to run the top level model in Accelerator mode, I see the error "redeclaration of enumerator". I'm using a top level model that contains various model references. If I open the submodel directly, I can run it in Accelerator mode. But it doesn't work when simulating the top-level model. It appears that Simulink is building a new header file for one of the model references "<model_name>_private.h" that contains code that duplicates and conflicts with the externally defined enumeration.