WaveHC Library Trouble
So the problem was that I did not read this comment carefully

/** SPI slave select pin. Warning: SS may be redefined as another pin
but the hardware SS_PIN must be set to output mode before any calls to
WaveHC functions. The SS_PIN can then be used as a general output pin */


"SS_PIN must be set to output mode before any calls to
WaveHC functions"

I read this and thought that meant whatever pin was being used as the SS pin needed to be an output, but it meant literally that pin 10 (the hardware SS pin) had to be set as an output regardless of whether it was being used or not.

So the solution is to add 

pinMode(10, OUTPUT);


to anywhere in the code 

Edit : also thanks @per1234 for pointing out the correct answer, I just didn't read your comment properly.