Eventide Staff
Try a CLEAR SETUP, then set the unit as you describe. If this doesn't help, try a different (and shorter) RCA cable. If this fails, contact support@eventide.com.
SP/DIF is not a very rugged format, and is sensitive to noise pickup and cable length. In particular, it should not normally be used above 48kHz.
The pitchshifters have a "minpitch" setting, but not one for max pitch. Sorry.