Hi! It compiles on my side. I added MSSR_API to the UMSSRBPLibrary class and the structs, added the plugin to PrivateDependencyModuleNames in the build.cs, also in .uporoject, regenerated the project files and then this compiles: UMSSRBPLibrary::SnapActor(Actor, FSnapSettings(),true, T, Res);
Which is your target platform? If it’s Android, did you included it in AllowList?