If the permissions disappear unexpectedly in AEM as a cloud service, ensure that you have added IMS users to IMS groups via Admin console and have included IMS groups in AEM local groups.
Adobe Experience Manager
Permissions granted to a user in AEM as a Cloud Service may unexpectedly disappear, resulting in the following symptoms:
Groups created in the Admin Console (IMS groups) are synchronized to AEM and treated as groups on AEM. Unlike groups created on AEM (AEM local groups), the IMS group must not be modified on AEM. The changes to the IMS group may get reset unintentionally, which leads to permission issues.
Examples of changes that cause problems:
Follow these steps to configure users and groups:
Add IMS users to new or existing IMS groups using the Admin Console
Add IMS groups as a member of AEM local groups
AEM built-in groups:
Set permissions on AEM local groups