it is less information you’ve presented and therefore difficult to answer.
But i try to answer
What is the parent class of this blueprint? For example if it is a widget you have to activate the input first before the BP recognize any inputs.
If this is not the case then try to use “Move Component to” instead of “Set Relative Rotation”.
Is “Static Mesh Component” a default “Static Mesh Component”?. Is it moveable? Click on the mesh component and in the details panel you will find an option to make the mesh static or moveable. Here you can find the “Transform” tab and under that tab you should see the “Rotation”. If not then create a custom Actor BP, create a USceneComponent as root and attach your “mesh” to it. Then rotate the USceneComponent or the Actor BP instead of the mesh.
Do you see the “Hello” string when running your project?