Reduce high pitched noise from idle stepper motor

I have the following setup:

Stepper motor: Bipolar, 200 Steps/Rev, 42×38mm, 2.8V, 1.7 A/Phase – https://www.pololu.com/product/2267

Diver: DRV8825, with current limiter VREF = 0.85v – https://www.pololu.com/product/2133

Power Supply: 12v 2a DC

When the steppers are hooked up to the power supply they make a very annoying high pitched noise while the steppers are idle. I am fine with a bit of noise while the stepper is moving, but would like them to be silent while stationary. I cannot figure out what is causing the noise. Here is what I have tried to reduce the idle noise:

• Reducing the current until the noise is gone (resulted in complete loss of torque when the current was low enough to remove the noise)
• Used a 5v 3a DC power supply (motor did not power on at all with this supply, I am still confused why it is rated for 2.8v but won’t work with 5v but will work with 12v)
• Engage the sleep pin while the motor is not moving (removed the noise while idle, but when it disengages sleep pin to move again its jolts slightly and causes the step count to be off and over time the motor is no longer accurate)

These are not the only stepper motors that I have that have this noise issue, the only motors I have that do not have this noise issue are smaller 350mA neema17’s and I think that is just because it has a lower amperage.

I have not been able to find a way to fix this issue. Are my configurations incorrect? What power supply should I be using? Is there anything else I can do to fix this high pitched noise while the stepper is idle. Any help will be greatly appreciated!