If you want a “generic class” that you can use with blueprints (UPROPERTY, UFUNCTION) etc. you need to derive from UOBJECT. Not an empty class.
Just to add a bit more colour - all of those U-macros are only available to UOBJECT class and any of its derivatives. The generated.h headers are actually created during the process of “compiling” your project (I put the term “compiling” in quotes because when you compile in unreal you directly or indirectly use the unrealbuildtool that does a lot more things than just compile. Somewhere in that process, the U-macros are processed and create the linkages to blueprint that you control with the U-macro parameters (EditAnywhere, BlueprintReadWrite etc…)