Why is the Dolby Audio equalizer not working?

A

AC Question

I own a ZTE Zmax Pro, and it seems that Dolby Audio only seems to work with anything other than Soundcloud (and Firefox too). I have tested it with other music streaming apps, and even the defualt music app on the phone, and they all work fine with the Dolby Audio equalizer. What could the problem be?

My brother recently bought a ZTE Axon 7 with Dolby Atmos, and it seems to work fine with any audio you throw at it (it's pretty great too!), so I'm hoping that will give some insight on the situation. Thanks in advance.