Slicer works great. If you are trying to slice through Fusion body (To get a DXF file to cut) I have a suggestion.
This is a part of my daily workflow it seems.
This is a light pipe for an LED display.
Turn on Construction in the browser, so your cutting plane will be visible. It should appear just below Sketches.
Start by selecting Construct> Offset plane.
Click on the face of your object, and enter a value. I often use -0.1mm, but you can slice it anywhere, as long as it slices where you want your profile to be.
Now create a sketch on the yellow construction plane you just made.
Select Sketch> Project/Intersect> Intersect In the dialog select “Bodies” not “Faces” and select the body again. Click OK.
You should now have an outline with a bunch of purple lines.
Fence select them all, Right click and select “Break Link”
They should all be blue now. Resist the urge to modify anything before exporting. If you leave it alone, it will cut in logical order , if you change it, the cutting order will be weird.
Close your sketch, and you can now export the sketch as a DXF and import to your favorite Design app.