Hello, sorry for the late reply, busy days / weeks / months.
You found quite a simple but serious bug: float rectangles passed to C++ are read as integers, ie all values of your float rect are rounded down to 0. That was probably a copy & paste mistake and I've just pushed the fix. However, there is no quick workaround for you right now.
I hope I can pack up another release one of these days.
Thanks for finding and reporting!