MTB Rear wheel noise once every revolution when not pedaling

[Danieloukos]

Hello everyone,

I am posting because my bike has been making these noises and they are getting really annoying and I am not sure if it is damaging the bike or not.
Every time i ride or even when I turn my bike upside down to check on it, the bike makes this clicking/rattling noise when I am not pedaling.(not the normal noise that you would think, it's something that wasn't there before.) I have taken the bike to the mechanics but honestly they don't seem to care and they always tell me "yeah i checked and there is no noise". So I need your help to find out what is this noise and how i can fix it(probably just needs some grease but I am not too familiar with bikes).
So to sum up, the bike makes noise :
1) Both when riding and when on a stand
2) Not when I am pedaling but right after
3) Once per revolution
4)When I pedal backwards the noise becomes worse
5)It seems to be coming from the axel/casette area of the rear wheel
6) From what I saw, nothing is touching the wheel/spokes(First thing that came to my mind is that it might be just some cable touching somewhere)

Here is a short video showing you the noise it makes :

https://imgur.com/a/VENsUFP

I would very much appreciate if anyone could help me!

Have a lovely day,
Daniel

[ReapThaWhirlwind]

You could have a bearing displaced in the hub.

You'll have to take the hub apart to see.

[ReapThaWhirlwind]

After checking the video, it looks like it's from the cassette guard or the reflectors.

Make sure the reflectors are pushed up the way up the spokes snug.

The guard will have to be removed or cut off. You can replace it if you want but it's not necessarily needed so long as you keep your low limit screw tight and snug to prevent the derailleur from over-shifting into the spokes.