that is strange and I know you don't like to read this: Works fine for me.
I today tested a different macro "<apple><a> + <s>" with a SpaceExplorer and 3DxWareMac 1.6.3 and 10.0.4. Out of curiosity - what does "s" actually do and what is different to "o"?
I must apology first, since you surely already did the following steps over and over, too, but just to avoid any misunderstandings, please try to reproduce them.
Here is what I did:
- open the driver's prefs pane
- add (if necessary replace) the application "Cinema 4D" in the prefs pane.
- select this new "Cinema 4D" configuration
- got to "Buttons" tab, "Custom Functions..."
- add "+" a macro and set a name to it (I called it "Fit Macro")
- add a Macro step "+", change the step type to "Keystroke" and set <none> to "o" by typing it in.
- select "Fit Macro" for the "FIT" button
Then in C4D: hitting the "FIT" button centers the object.
Well, it actually took me a few moments to find out that "o" needs to have an object selected (same with "s"). Otherwise, nothing happened - same thing as if "o" pressed on the keyboard.
Btw. you can check if the config correctly addresses C4D if you assign "Increase/Decrease Sensitivity" to "+"/"-" respectively, leave the driver's prefs pane open on the "Device" tab and then go to C4D (make the C4D window active) and press "+"/"-". If the config is correct you'll see the "Overall speed" slider change (as long as the C4D application/window is active) while you press the device buttons.
In this case, the macro will (or lets say, should) also work.
Last question: Is the "Fit Macro" in the prefs assigned to "FIT"?
Please let me know, what your results on these steps are!