Please consider following on user mailbox -
1) Call SyncFolderHierarchy repeatedly on msgfolderroot till no changes are returned, store sync state returned. Use EWS impersonation for access.
2) Change permissions on one of the folder returned.
3) Repeat step 1 with stored sync state.
It has been noticed that folder for which permissions are changed is not being returned. Documentation does mention that this should work. This is being tried on an Exchange Online mailbox.