SBL2360S Sinusoidal/Encoder issue

Hello,

We are testing a sinusoidally wound frameless motor with 8 pole-pairs and a 2048 ppr incremental encoder. I have read the manual and have everything set up to the best of my ability. During startup, as expected, the motor does the reference seek procedure and always returns success, according to the command output. I have set it up to run off of an analog joystick and it runs very nice and smooth in both directions if I keep the rate of change low. But when I try to accelerate very quickly, it sometimes just freezes up and makes a grinding sound. If I gradually reduce the joystick command it will start to move again.

See the video here for what I am talking about:
youtu.be/FxGnjbPehBY

I set the acceleration and speed limits to the maximum allowable value, so I don't think it's trying to limit speed or acceleration. I also do not have any sort of stall detection or current action happening.

Is this a problem that has happened before? Any ideas how to fix it?

I can take intermittent data logs, as the USB connection keeps getting knocked out during big movements from the motor unfortunately. See the attached images for an example during a particular instance where this "grinding" sound happened.





Thanks.