We raised the ticket (526410) regarding the login issue. The issue was when we logout from Veeva Vault then session is getting closed at Veeva End or browser end only. If we choose switch user option and mentioned other User Id then we get logged with the previous ID not the provided one. This is because Veeva Vault doesn't support Single Logout Feature.
So we request you to make Veeva Vault supported to Single Logout Feature too.