I have written an interrupt handler inside a sketch and copied essentially the same code to a C++ class. It works fine in the sketch but not in the class.

I remember stumbling across this awhile ago but I don't remember the solution. How do I get an interrupt handler working inside a C++ class?

I have included my test program and my .h and .cpp files. I am trying to get four variants working:
1) .ino file handles using polling (works)
2) .ino file handles using interrupts (works)
3) .cpp file handles using polling (works)
4) .cpp file handles using interrupts (does not work)