I went through this exact same process a couple months ago. Even though the $ has shown up in the settlement account, the process may not be totally over. You can't move that $ into stocks or bonds until the transaction says "final" or "complete" or similar. If the transaction is still "pending," even though it has shown up in the settlement account, then you can't move that $ into other funds quite yet. If the $ showed up a matter of days ago, then I think that is the issue. If the $ has been in the settlement account for a month, then that's a different matter and Idk, call Vanguard as has been mentioned.
This is all with the huge caveat that I'm a new Vanguard member as well, and by no means an expert.