The driver seems weird though. If it says 60V spec, and you can set the current (usually with a DIP switch setting), it should handle everything in a 56V setup.
It is supposed to limit current, and it is supposed to operate with 60V input, and it is supposed to operate a motor and hold position, when needed, (ie a stall) so what should be wrong?
Is the 56V clean DC?
Are you running through a rectifier bridge with adequate filter caps?
The only other possibility is that there's some current rating for the driver (not the current setting), and it doesn't like the low resistance of your motor @ 56V -- 56V pushes too much current for the driver max rating.