Let me share what I have learned from two stays at SBP this year that didn't post automatically. Vistana VSE) explained that if everything is working correctly, your elite night credits will post 14 days after checkout. If you don't see them after 14 days you have a problem.
First, make sure that the email associated with your VSE account is the same email you use for your Marriott Bonvoy account. When you are logged into your VSE online account, go to account settings and check your communication and security settings and change your email address in both of those places to match the one you use with Marriott.
When you check in at the VSE property, make sure your Marriott Bonvoy number is in your reservation and when you check out double check that it is still there because I've experienced where it drops out during my stay.
If you do not receive elite night credits after 14 days, send an email to
stay.add@marriott.com with a title that says elite night credit request and to which you have attached your folio from checkout. Make sure you send this email from the same email account that is associated with your Marriott Bonvoy account or else your request may fail. Don't reference receiving any points anywhere in your email because it has to be focused on elite night credit for them to process it. They will automatically add in your welcome bonus and any points for charges during your stay when they post the elite night credits.
If after attempting this you are still having a problem, your best bet is to call VSE and have them call Marriott with you on the line to solve this problem.
I hope this tribal knowledge helps!