Yes, known issue. Someone may know a workaround. I don’t.
I was just going to check this out. I tried out this bug on a bitmap before, and I believe that 180 degrees and one of the 90 degree rotations (I can’t remember if it was CW or CCW) showed problems. I was going to see if the 90 degree rotate in the other direction worked and suggest that you just do that twice get your image flipped 180, but it seems that the bug isn’t happening on my computer anymore, so I can’t even check to see whether or not that’s a valid suggestion! Now that’s strange… try it anyway though.
If you rotate the canvas twice 90° CW, you can get a 180° rotation withouth the ‘effect’.
90°CCW is broken.
I set an action for the clockwise rotation, but it’s still funny that PS can rotate a cmyk image at some arbitrary %, but can’t turn a bitmap. Seems like that would be an easy patch compared to some bugs.
Workaround would be to use an earlier version without the bug, surely?
Yes, it’s a known problem on Multi Processor machines.
Disabling MP Support will fix it for the time being.