Updated on 04-09-2023 with release number.
As stated in release notes of version 22.0.202315.61476, released on 11 april 2023, it is now mandatory to use Webservice Communication in Intercompany APP.
From version 22.0.202335.72696, released on 1 September 2023, we will let existing users, not using this setting, aware that this is now mandatory- and guide them to set it up manually. In a later release this year we will force this setup to all existing installations, on Saas.
As of now, there has been added an action on the partner card, to set the value manually. This is only visible if the "Inbox type Web Service" field is not set to true.
Please also see our article about how to setup Oauth, which is required to run Intercompany with Webservice Communication.