Set-MailboxMessageConfiguration cmdlet has no effect in Outlook on the web

also searching in vain for information on why they have stopped referencing local signatures in current outlook versions before they've released the replacement system for managing Exchange Mailbox signatures. says it's coming soon for years at this point but doesn't seem that the client deprecation train has been halted and is still chugging away towards the cliff without a peep of progress on getting the replacement system available to customers

if anyone has any more information on how this is planned to become available or options we've got to continue to use the long standing system until such time as the new process is properly published that would be very welcome