Private Link not working

So, I have been waiting years for this to become possible! Thank you!
I have listed all my current scores as private, so as to host only from my domain.

1) When I upgraded to 3.x, this issue began, although, I think the private linkis very new. Anyway, it ain't
working.
2) All of my clients get a "page not found" error along with MuseScore options. So my iframes ARE connected to Muse, and getting these errors. (It doen't make sense to workaround, as I have been by providing them with my MS credentials)

I have tried with both private and default link embeds. No dif. Pge not found.

3) Ironically though, my scores that are uploaded w/MS 2.x, are not only available through my embeds,
but without need of credentials. As they once were when I uploaded them 2 years ago. Concerned that 2.x scores have no longer private protectio?
Also, that the 2.x embeds were prior to the private link option, so those embeds are using the original code.

Example issue page
https://personalpianoteacher.com/pentabird/

Thanks IA !