Add-PublicFolderClientPermission: Object reference not set to an instance of an object.

Running into an issue with adding public folder permissions in Exchange Online. I've used this PowerShell script for a few years without any issues, but suddenly getting this error no matter what I try. I do have Owner permissions and there are Default and Anonymous permissions on the public folder, tried completely removing and reinstalling the ExchangeOnlineManagement module as well.

Anyone else having this problem?

    $PF = Get-MailPublicFolder -Identity "\pf1"
    $User = Get-User -Anr "User1"
    $AccessRights = @( "ReadItems", "CreateItems", "EditOwnedItems", "EditAllItems", "FolderVisible" )
    Add-PublicFolderClientPermission -Identity "\$($PF.Id)" -User $User.UserPrincipalName -AccessRights $AccessRights -Verbose

VERBOSE: Returning precomputed version info: 3.9.2

VERBOSE: Requested HTTP/1.1 POST with 227-byte payload

VERBOSE: Received HTTP/1.1 response of content type application/json of unknown size

VERBOSE: Query 1 failed.

Add-PublicFolderClientPermission: Object reference not set to an instance of an object.

Thank you