Cross-tenant mailbox migration in now in Public Preview

Hello all,

I'm still strugling to make a cross tenant migration for test shared mailbox to work. I get an error every time I run a test while the source legacyExchangeDN is properly set as target EmailAddress:

On the source tenant:

> Get-mailbox test | fl ExchangeGuid,ArchiveGUID,LegacyExchangeDN,UserPrincipalName,PrimarySMTPAddress,emailaddresses

ExchangeGuid : ecc73bc6-012c-4a42-9708-d5221d7c5d85
ArchiveGuid : 00000000-0000-0000-0000-000000000000
LegacyExchangeDN : /o=ExchangeLabs/ou=Exchange Administrative Group(FYDIBOHF23SPDLT)/cn=Recipients/cn=b2c3d55fb1004577b5779c5e8066aca4-test
UserPrincipalName : email address removed for privacy reasons
PrimarySmtpAddress : email address removed for privacy reasons
EmailAddresses : {SMTP:email address removed for privacy reasons}

On the target tenant:

>Get-mailuser test | fl ExchangeGuid,ArchiveGUID,LegacyExchangeDN,UserPrincipalName,PrimarySMTPAddress,emailaddresses

ExchangeGuid : ecc73bc6-012c-4a42-9708-d5221d7c5d85

ArchiveGuid : 00000000-0000-0000-0000-000000000000

LegacyExchangeDN : /o=ExchangeLabs/ou=Exchange Administrative Group(FYDIBOHF23SPDLT)/cn=Recipients/cn=a9cc9be87aa945d4bfe402efe9b1ff71-test

UserPrincipalName : mailto:email address removed for privacy reasons

PrimarySmtpAddress : mailto:email address removed for privacy reasons

EmailAddresses : {X500:/o=ExchangeLabs/ou=Exchange Administrative Group(FYDIBOHF23SPDLT)/cn=Recipients/cn=b2c3d55fb1004577b5779c5e8066aca4-test,
SMTP:email address removed for privacy reasons}

>Test-MigrationServerAvailability -EndPoint "MIGENDPOINT" -TestMailbox "email address removed for privacy reasons"

RunspaceId : 1c527d47-8499-45ef-8dde-748ae55f6f4d
Result : Failed
Message : One or more X500 proxy addresses or legacyExchangeDN of source mailbox are missing on target MEU as X500 proxy
address.
SupportsCutover : False
ErrorDetail : internal error:Microsoft.Exchange.Migration.MissingProxyAddressException: One or more X500 proxy addresses or
legacyExchangeDN of source mailbox are missing on target MEU as X500 proxy address.
at Microsoft.Exchange.Migration.MigrationEndpointVerifier.ValidateCrossTenantMailboxInfo(ADMailboxRecipient
targetADMailboxRecipient, ADMailboxRecipient sourceADMailboxRecipient, MailboxOrMailUserIdParameter
targetMailUserIdentity, TaskErrorLoggingDelegate writeErrorDelegate)
at Microsoft.Exchange.Management.Migration.MigrationService.Endpoint.TestMigrationServerAvailability.InternalProc
essCrossTenantScenario()
at Microsoft.Exchange.Management.Migration.MigrationService.Endpoint.TestMigrationServerAvailability.InternalProc
essEndpoint(Boolean fromAutoDiscover)
TestedEndpoint :
IsValid : True
Identity :
ObjectState : New

I'm running out of ideas now. I've also recrated the organization relationship and admin consent to make sure but still no luck.

Additionnal check done:

On the source tenant:

> $mbx = Get-mailbox -Identity test
> $mbx.LegacyExchangeDN
/o=ExchangeLabs/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=b2c3d55fb1004577b5779c5e8066aca4-test
> $mbx.EmailAddresses
SMTP:email address removed for privacy reasons

On the target tenant:

> $mbx = Get-mailuser -Identity test
> $mbx.LegacyExchangeDN
/o=ExchangeLabs/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=a9cc9be87aa945d4bfe402efe9b1ff71-test
> $mbx.EmailAddresses
X500:/o=ExchangeLabs/ou=Exchange Administrative Group(FYDIBOHF23SPDLT)/cn=Recipients/cn=b2c3d55fb1004577b5779c5e8066aca4-test
SMTP:email address removed for privacy reasons

Thank you in advance for your help.