I'm sure this is completely obvious, and an accidental keystroke somewhere....but.
I have splines, and at times when I try to manipulate the tangent handles, and points, I can only move along 1 axis. They seem locked, but the X,Y,Z buttons at the top of the screen are all active, they don't seem to affect the splines. This problem goes away, and it seems to be some mode I'm accidentally going into. This seems to be a new issue for me in V11, and it's driving me nuts. Someone help with something I know is right in front of my face.
It's been a while since you posted and you may already have figured it out, but for those who haven't been so lucky...
Apparently, double-clicking on an axis handle will lock Cinema4D's move/scale/rotate tools to that axis. Axis handles are the red/green/blue arrows you use to move your object around in the viewport. The currently locked axis (if any) will be highlighted in yellow. To unlock, simply double-click on that axis' handle.