Having used MM for several years and in numerous versions, this is the first time I have encountered this issue.
I installed the new Premium Edition only this morning. As a default, because much of my work is for video, my external MOTU audio interface is set to 48kHz sample rate. Once the new version was installed I quickly tested it by having the default Piano VSTi in track 1 and pressing middle C on the on-screen keyboard. Immediately my ears told me this was not sounding the "proper" middle C but was nearly a tone sharp (so sounding a rather flat D). (As a retired music teacher I am "blessed", or perhaps cursed, with Perfect Pitch, hence my reaction to this mis-pitched note.)
This was not an issue with the specific VSTi since all others that I tested gave the same result. I also checked this against my Nord keyboard, where middle C is 256Hz, the standard frequency setting.
So I changed the sample rate of my interface to 44.1kHz and, of course, middle C was now middle C, rather than the rather flat D. Reverting to 48kHz and the mis-pitching returned.
As I said, I have never encountered this before, having used 48kHz SR with earlier versions of MM without the problem being encountered.
Before I raise a Support Ticket on this I'm interested to know whether anyone else has encountered this and knows how to resolve it, other than by changing the sample rate of my audio interface every time before I open MM (I discovered that I cannot change the SR of the interface whilst MM is running because that results in audio silence!)
Any and all ideas very gratefully received!
Jeff