GLSLang: EOptionAutoMapLocations/setAutoMapLocations and Reflection with GLSL

Hey, I have shaders that are made by end-users. Those shaders don’t specify locations for vertex inputs, so I use setAutoMapLocations(true) when compiling the GLSL code. This allows the code to compile fine, however when trying to use Reflection to find the locations those vertex inputs were assigned to, I can’t get the location. I’ve tried spirv-reflect, spirv-cross and the reflection that glslang has built-in. All of these just return location=0 for the vertex inputs that don’t explicitly specify a location.

Am I missing something? I need this location to be able to render right? Or is there an alternate way specify the vertex inputs from the information I get from reflection?