I have 2 Okta implementations, a developer sandbox and a large multi-application production instance. I have a custom built application that has been experiencing some awkward Okta issues. The custom application receives a 400 Bad SAML Request error late in the day before 6pm in both my sandbox instance and my production instance. Once 6pm CST hits, I can authenticate successfully against both instances. I have been able to recreate this behavior over multiple days now. I haven't been able to find anything in the logs and the SAML request is obviously exactly the same from the client side before and after 6pm CST. Any ideas as to what might be going on here? Thank you for your time!
Can you provide more details about the custom app? As this is not an app that is in OIN, this may require a deeper investigation, and as such, I recommend opening a Customer Support ticket to further investigate the issue and help you fix it.