YouTube demonetized my channel because of reused content. This is sadly a common issue. If you upload someone else’s content you run into this issue.
Especially in the case of music channels there are many demonetized:
Even if you have the full rights from the labels to share the track with your community, you will be demonetized! I am in contact with a few music labels. One of them has about 70+ artists under contract. I have the written permit to share them and YouTube says it’s reused content and cannot be monetized. Sadly there is no solution. All of those music channels or gaming montage channels have the same problem. I don’t know if i will run the project anymore. Very sad because i reached more than 500.000 views per month.