I received a "Notice of Intention to Obtain a Compulsory License for Making and Distributing Phonorecords" regarding a song I had submitted to Spotify that was derived from Pro Audio Unlimited Soundpool loops. One, is this permitted under the Audio Pro Unlimited License and two, how do I proceed if it is or if it isn't?
As far as the MAGIX licensing aspect of this question is concerned, I can confirm that you're well within your rights to commercially distribute a song you made with the help of MAGIX soundpools, if you own the pro license for those soundpools. This includes any kind of traditional, mechanical distribution, as well as digital or streaming distribution, such as Spotify. So, that's that.
I cannot really speak to the significance of this notice you received from Spotify and how this relates to your work. If you search for this online, you'll find a lot of legal mumbo jumbo, and maybe you'll really need to seek legal advice. However, maybe you'll find this thread helpful, where someone was in a similar situation:
As you can see, this might very well be some sort of mistake on Spotify's part. This might especially be true when considering the way your song was created and how many people may have used some of the same content in their songs. So, in this regard, this situation may be somewhat akin to the incorrect copyright strikes our users tend to get on their songs on YouTube. Communication with Spotify might be the key here.