If your Circular Saw is not cutting properly, ensure the Circular Saw Blade is in the correct orientation/direction, and that the Saw has been fitted with the correct size blade (for the R18CS-0; 165mm Blade) as shown below:
Make sure you’re using the correct blade for your material. For example, a higher tooth count/TPI blades may be more suitable for slower speed finishing cuts.
You should also regularly inspect the blade for any signs of damage (blade is bent, broken teeth, wear and tear, etc), and replace if necessary - ensuring to replace the damaged/broken blade with one of the same size.