Sorry for this late answer, when I first answered you,it was quite late.
Yes, you are right, I think I understood something else.
I thought that you had the option "always on top" switched off, therefore having SliderDock visible but partially hidden under another window.
I have now noticed that the code for the keys to rotate left and right have a different code for visibility check than the one for launching an app.
I think that might be the reason why you have this problem. But strangely this doesn't cause a problem on my pc so I couldn't notice that problem myself.
I have changed the code so it might fix this problem.
It will be included in the next version that I will release very soon hopefully.
But since I can't really test if whether or not it will fix this problem, I'll need you to tell me that if it's alright with you.
Right now can you test with the version you have if you hide sliderdock, then press left key to rotate the icons then unhide SD.
See if the icons have rotated or not.
IF they didn't rotate, then I believe that the fix I made will indeed be what you need.