Exception when trying to use class from dynamic dll

I have a new module to the engine under the 3rdparty folder. I have added both binaries in engine/binaries/thirdparty and include and libs under engine/source/thirdparty. I have created a build.cs file in the source thirdparty folder for the dynamic library I’m trying to integrate. The build module file defines the include path, the library path and the runtime dependencies. I’ve added the runtime dlls to the delay loaded list.
As a test I have modified a file in the Core Module and tried to instantiate a class coming from the library. I have added the module to the Core.build.cs using AddEngineThirdPartyPrivateStaticDependencies. Using AddEngineThirdPartyPrivateDynamicDependencies didn’t work. The editor builds and links and runs until I try to create an object from the class define in the new module I’ve added which depends on the module dlls.
I get an Module Not Found exception. I haven’t found a way to resolve this.
I could get around this by copying the dlls to the editor binaries folder. That seems like a work around.
Is there a way to get the dll path for the module added to the editor dll search paths ? Shouldn’t this be controlled from the build.cs file ?
Any help appreciated.