I have a character sheet for a level 17 character who has 15 levels of Wild Magic Sorcerer. The character sheet shows that she has one 9th level spell slot (she should have no 9th level spell slots as a level 15 sorcerer). Also, when I level her up to the next level putting her at 16 levels of sorcerer, she should now be able to choose a 9th level spell to learn but no 9th level spells show up in the list. In fact, even if I level her all the way up to level 20, 9th level spells never show up for her to learn.
So the thing about multiclassing is: it follows the multiclassing rules.
When you multiclass 2 spellcasting classes you combine their level and get slots based on that. 17 spellcasting levels is when you get 9th level slots.
However, you learn spells based on the individual class level. You learn 9th level spells at class level 17.
If you were changing levels in the builder with the spell selection open, that doesn't update live (not a bug, just websites working the way they do). Change your sorcerer level to 17 or above, then check spells, you should be able to select 9th level.
Hopefully that addresses all of the (non-bug) issues you were having.
I have a character sheet for a level 17 character who has 15 levels of Wild Magic Sorcerer. The character sheet shows that she has one 9th level spell slot (she should have no 9th level spell slots as a level 15 sorcerer). Also, when I level her up to the next level putting her at 16 levels of sorcerer, she should now be able to choose a 9th level spell to learn but no 9th level spells show up in the list. In fact, even if I level her all the way up to level 20, 9th level spells never show up for her to learn.
Can anyone take a look and see if it is a bug or just operator error?
https://www.dndbeyond.com/characters/34585603
So the thing about multiclassing is: it follows the multiclassing rules.
When you multiclass 2 spellcasting classes you combine their level and get slots based on that. 17 spellcasting levels is when you get 9th level slots.
However, you learn spells based on the individual class level. You learn 9th level spells at class level 17.
If you were changing levels in the builder with the spell selection open, that doesn't update live (not a bug, just websites working the way they do). Change your sorcerer level to 17 or above, then check spells, you should be able to select 9th level.
Hopefully that addresses all of the (non-bug) issues you were having.