Hi @lee,
Unfortunately, this is not a SW bug, but rather a new feature coming to Edge 116, where some work browser policies aren't available for the Enterprise personal browser (MSA profile, profile that is connecting to an MSA/personal account). These work browser policies include "InternetExplorerIntegrationLevel" and "InternetExplorerIntegrationSiteList". You can refer to Policy filters for the Enterprise personal browser for more information.
To avoid this, you can choose to use Work profiles since it seems that you have a group of users to manage. Or you can use local site list to stay in IE mode.
You can also share your feedback on this new feature. To send feedback in Microsoft Edge, please press Alt+Shift+I. We would value your feedback. Thanks for your understanding.
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Best Regards,
Shijie Li