smartmotion mid city gear issues

[Buggy]

I have a midcity and when changing gears it makes a reving and clunking sound. If i stop pedaling it changes fine . It doesn't seem as bad when in torque mode compared to power mode. If you touch the brake lever it changes gear ok. Any thoughts on what could cause this.

 

[neptronix]

What's a midcity? what make/model motor does it have?

 

[Buggy]

Smartmotion MidCity MED 27.5

 

[Buggy]

It has a Dapu mid drive