Modifying Mailboxes using delegated partner credentials

My goal: To be able to administer our partner mailboxes i.e. Converting mailboxes to shared, set forwarding rules etc… in powershell

Current status: Script works as it should, connects me to my partners exchange online environments. Running Get-mailbox works fine; however, when we get to changing mailbox information it gets tricky.

Issue: When I run the command below I receive the error: The remote server returned an error: (401) Unauthorized…

Set-Mailbox -Identity email -Type Shared

Oddly enough, if I run the command below, I get no error at all it commits the change of display name just fine.

Set-Mailbox -Identity email -displayname NewName

I have a test tenant I can work with that is solely in Office 365, meaning no hybrid configuration.

I will happily paste my script however It keeps getting blocked as spam even after me sanitizing it of all confidential info (it doesnt have any to begin with).

Have u checked ur rights on the mail box for ur user ?