Hi, welcome to the Magix forums.

Since there is such limited information in your post - we don't know anything about your computer, OS, or even which version and variant of MM you are running - any reply is likely to be highly speculative! Please read this post to see what we really do need to know! 😀

However, pure guesswork on my part, both MM and Discord are using the same ASIO audio driver. ASIO can only handle ONE audio source/output at a time (there are ways of circumventing this, sort of, but they are not especially easy to do). This "single source" is one of the limitations of ASIO. Hence, my guess is that MM is set up to (entirely correctly) use an ASIO driver and this driver cannot be released to allow Discord to work.

Jeff