I'm trying to figure out what is wrong with the reply tracking in Outlook for e-mails that are sent from OWA plugin.
Lets say that we have two incoming messages in Inbox: email_1 and email_2. I reply to email_1 using the Outlook "reply" button and reply to email_2 via OWA plugin (using the sendItem function from office.js library which calls the Office.context.mailbox.makeEwsRequestAsync function). Then I check the Inbox again and see that email_1 is marked with "replied" icon in a list and with a message "You replied to this message on ..." when I open it. And email_2 doesn't get neither "replied" mark nor "you replied to..." message.
Both replies can be found in the Sent folder. I've tried to compare their headers and both have the In-Reply-To and References header lines pointing to correct messages. The same behavior can be spotted in Outlook for Windows and Outlook for MacOS (may it be an issue of Exchange server?).