Things are possible in real life that CAM software is not built for because it is rare and unconventional way to do things.
If using same tool to run internal and external groove, you CAN program it in Fusion but you will have to do additional G-code edit.
You can set right hand ID grooving bar for ID grooving running with CW spindle direction, duplicate it, give it different number and change its setup to run with CCW spindle rotation.
In that configuration tool will cut outside groove with CCW spindle direction, shown with insert pointing up, as shown in model attached, from positive direction, now you mirror X axis, G2, G3 and I moves within that tool path (if using I and K for arc center).
This will make tool approach part from negative side of center line and work towards positive side or X0.
This makes single tool set as ID grooving bar on upper turret work as both internal and external tool providing you have enough X axis stroke to go to negative side of X0 and do outside work.
The key here is to mirror X axis of external tool path after generating tool path.
You cannot display ID tool outside of part and on negative end of X0 in Fusion, not meant to work that way so you get error but that doesn't mean you can't program it, simply change sign for all X (and I) coordinate, reverse G2 and G3 moves and you are in business.