I have followed the guide in the official documentation. Additionally, I created a virtual host for invalidation_only though that was not explicitly in the docs, but I found that as a recommendation in this forum.
What is happening is:
I have /content/sitea and /content/siteb.
I send the invalidation request for /content/siteb but in the dispatcher logs what I see is:
If I request /content/siteb/test.html, I get the test.html correctly and the file is created, but because of the incorrect .stat file being created in /content/sitea/ I have to delete the file again in order to clear the invalidated file.