I have selected several folders with .mgu and .sgu songs, I have rebuilt song picker.
There are many (most) songs that will not load.
I am using Big Sur and 2020 build 422.
Any ideas?

When you say that most songs are not loaded, does that mean some songs are there and some are missing? Do all the songs have the .MGU or .SGU file extension?

We have a 423 build update posted. Please download and install it and see if that fixes your issue.

https://www.pgmusic.com/support_macintoshupdates.htm