Mail Forwarding for Internal Senders Error: "The object is not found in Office 365" (4328938)

Mail Forwarding for Internal Senders Error: "The object is not found in Office 365"

For our test situation, we've migrated user and checked the "forward mail" button. Mail from external senders seems to be sent to the target mailbox, but not mail from internal senders (other mail users on the same source Office 365 tenant, that have not been migrated yet). No blocking in place on the source tenant.

Mail coming from external senders is being forwarded, indicating that the forwarding part is OK. This may be related: I attempted to do a full
switch of our test account, and received an error:  "Error    Mailbox Switch    The object is not found in Office 365"

However, I am not sure what that refers to. All other migration steps appear to be correct.

Do you have more details on this error?

Something has changed with the target object, and a new match is required.

Confirm the Migration Admin account is a member of the Exchange roles (https://support.quest.com/kb/250237/error-creating-target-session-the-account-does-not-have-permission-to-impersonate-the-requested-user)

Run the following steps:
Run the Match task and select 'Clear Existing Matches'
When this completes, run the Match task again and Match the user or Match from File if this is what you did before. Confirm the target upn is correct.
Run a migration
Run the Switch

If this fails, try the following:

Remove the user from ODM
Run a new Discovery
Match the user
Migrate mail
Switch mailbox