After you select the tool, did you click someplace in the drawing area, and after you did enter your values, did you hit enter, and are the layer you draw on visible ( open eye )
Just a few toughts.
V18, V19, V20, V21, 2015/ 16/ 17/ 18 Pro. Platinum
Deluxe V20, V21, 2015/ 16/ 17
Windows 10 Home Premium 64 bit, 32 GB
NVIDIA Geforce GTX 780m, 1 GB