Thank you for your quick and very helpful response.
Even for me, it was simple to rebuild this easy BP. 
It seems that the cursor location is based on its actual position on the screen when starting the game. I tried to center the cursor as shown in this video:
But now the cursor is at the top left of the screen, which is the same issue as mentioned in the comment under the video. So I disabled the code again.
I tried to start the game with the cursor in the middle of the crosshair. Here, I noticed that the cursor seems to move faster or slower than the viewport change/camera view, or it might be offsetting? Iām not sure about that.
The crosshair is pointing at the wooden sheets (BP to open the menu), but the click actually refers to the furniture to the left/below it.
Thank you so far.