Not receiving <InReplyTo> tag in EWS GetItem response if mail subject changed in reply

Hello,

I have an add-in that I run in Exchange Server 2019. When replying to an email, my add-in requires some information related to the parent email. For this, I use the EWS GetItem API. In the response, I get an <InReplyTo> tag, where I find information about the parent email.

See below example for more info:

The issue is that if I change the subject in the reply, I do not get that <InReplyTo> tag in the response, and hence cannot access parent email information.

This issue is only observed in Outlook on Mac (classic UI).

Any information, workaround, or timelines on a potential fix for this issue will be greatly appreciated.

Do let me know if any further information is required from my end.

Thanks,

Raghunandan Kumbhar