Public Folder Permissions lost after migratiing to O365

Hello together,

a customer faces the following problem. He is moving his exchange mailboxes to office 365.
The pubic folder are hosted on another forest. This exchange server is on prem.

He could see that if he is migrating the mailbox to O365 the public folder permissions on ev side gets lost. The user are unable to open archived public folder items.

On the permission browser the permissions are gone for that migrated user.

In a dtrace we can see the following while synchronize:

769392 08:16:15.049 [5084] (PublicFolderTask) <9520> EV:H {CEx2kMailboxPermissions::getmailboxsecuritydescriptor:#145} Failed to list mailbox permissions for ********* whilst synchronizing due to a missing Active Directory attribute msExchMailboxSecurityDescriptor
{CEx2kMailboxPermissions::GetMailboxUserList:#584} **********Error [0x80040C9B]

I found the technote which described the error we could see in the dtrace.
https://www.veritas.com/support/en_US/article.100047606?profileURL=https%3A%2F%2Fvam-profile.veritas.com%2FVAMSSO%2Findex.jsp%3FssoID%3D1600779870698Uu91j156D316c7f5v4NXq3yQ44nnx67cjS72X

Is this related to the behaviour from the customer that the permissions are gone after migrating?

Thanks in advanced,

Lucas