Marketo and Microsoft product & engineering teams are working closely to drive MSI compatibility with Microsoft’s Unified Interface (also known as Microsoft PowerApps). Full compatibility is expected to be delivered by December 2019. Until then, users are encouraged to continue using MSI on Microsoft’s Classic Interface to maintain MSI functionality.
Please note this work is in progress and time estimates can vary based on unforeseen factors that may impact product engineering.
UPDATE - This upgrade will be a part of Marketo Jan 2020 release