You have already raised the issue of VSTis not appearing for you in MM2021 but it is not a problem for at least a substantial minority of users. IMO, to name something as a "bug" it must be reproducible by at least a substantial number of other users.
I have a number of non-Magix VSTis on my system, all of which are accessible to MM 2021.
As a result, I am going to close this thread. Please keep all discussion of your problem in your original thread.