I believe that there are some missing albums from the above two artists as detailed below:
Bee Gees- Anything released before 1968 (e.g., Spicks and Specks (1966)) and anything between 1980 and 1990 (e.g., One (1989))
the Beach Boys- Still Crusin' (1989), Summer in Paradise (1992), Stars and Stripes Vol 1 (1996), and Songs from Here and Back (2006)
Why are these albums missing and when will they be made available on Spotify?
Hey @DanT2014! Welcome to the Spotify Community!
Spotify would love to have everything available everywhere but sometimes things can be a bit complicated. Read more about that here. Also, be sure to check out Local Files, if you've got the music files on your device.
Take care! 🙂