If this is related to the Apple CNA, this is not the first time Apple has made changes to their CNA that end up breaking portal flows. Cisco has no involvement or control over Apple software development, so this typically involves development effort to identify and implement a workaround, which takes time. If you have not already done so, please open a TAC case to investigate further and track this potential issue and any potential in-flight enhancements.
A common practice to avoid these potential CNA issues with portal-based flows is to use one of the methods to bypass the CNA documented here. Leveraging these bypass methods does involve training the users to open a browser on their device, which is typically included in the communication plan to the end users when enabling/enhancing end-user services like BYOD. Doing so, however, helps mitigate future potential issues with portal-based flows breaking due to vendors changing something with their CNA.
