Hi brcallicott, thanks for the feedback!
If you are using a conditional access policy that only leverages the “Require approved client app” grant access control, Microsoft Lists will be considered one of the approved apps after May 14. You must enable Intune APP with Microsoft Lists to ensure it meets the full data protection needs of your organization. However, we strongly recommend that you update your conditional access policy to take advantage of the “Require app protection policy” grant access control. For more information on the recommended policy configuration, see: Scenario 1: Microsoft 365 apps require approved apps with app protection policies to learn more.
If you continue facing an issue with your conditional access policies not working as expected, please open a support case via the Microsoft Endpoint Manager admin center's Help and Support blade or any of the methods here, as this will help the team capture all the information needed to resolve the issue.