[QUESTION] Buzz problem with new pedal

Just bought a new stompbox pedal (Horsekick Pro) and a weird noise is happening through my amp. Video of the problem:

https://vimeo.com/223182449

Signal chain is guitar -> stompbox pedal -> amp. I've tried it with different amps and guitars and the noise happens randomly whenever the pedal is in the signal chain, and never when it isn't. My amp has two channels as well, and the buzzing never happens when the stompbox is ran through it's own channel, only when it's in the signal chain with the guitar and the amp

Have I just got something that's defective on arrival or am I overlooking something here? The troubleshooting I've done seems to rule out the possibility of it being anything other than the pedal, and there's no way it should be acting like that out of the box if it's working as it should.