Correct. A sibling-owned asset, including a sibling-owned 529 account, does not get reported on Profile. It is not an asset that is potentially available for the student’s college expenses.
Some plans do not allow a change of ownership. You will need to look on the plan’s website or contact the plan administrator.
A 529 account owned by a non-independent student is always reported on FAFSA as a parent asset. It’s reported on Profile in the student asset section (question SA-110A), but it’s up to each college to assign the account as a student or parent asset based on the school’s institutional FA policies. Some Profile schools, typically those that more closely follow the federal methodology, will count a student-owned 529 account as a parent asset.