I use the filters exactly like that, to “forward” tickets to a specific group for categorization.
Are you sure the emails are being sent to service@domain.com? Can you check in OWA of the mailbox?
I would setup the rules at office365 end, so emails sent to ticket@domain.com is moved to folder “ticket” and emails sent to service@domain.com is moved to folder “service” and then add the accounts in Zammad specifying the folder Inbox/ticket and Inbox/service on each account.
That solution works for us, and maybe it will help you solve your issue
I know you already solved the issue but I think the suggestion with the Filter on the “To:” field has to work. We had the same issue and solved it by using a regex filter. The problem was that we had two similar email addresses and therefore both filters were activated: eg. support@zammad.com and vip.support@zammad.com