It works here, draw a closed shape with Spline by Control point, esc to exit tool, explode to polyline, Select Clip tool, Select pic and then the polyline.
The polyline get hide by the pic so i need to remember about where the polyline was to click on it.
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