Our application is an add-in developed in react (typescript) and makes use of the microsoft graph apis to do certain actions.

Our add-in sets three headers (via patch with microsoft graph api) consecutively on a draft email and then sends it (via microsoft graph api) and we saw that sometimes the first one is not being set. (the second and the third are set correctly). On the browser version of Outlook this never occurs, but with New Outlook for Windows it happens pretty regularly.
We get our auth token through MSAL.

axios
.patch(
${microsoftGraphAPIUrl}${messageId},
{
singleValueExtendedProperties: [
{
id: 'String {00020386-0000-0000-C000-000000000046} Name ' + name,
value: value,
},
],
},
{
headers: {
Authorization: 'Bearer ' + authToken,
'Content-Type': 'application/json',
},
},
)

Could this be related to an incompatibility between New Outlook for Windows and Microsoft Graph?
If you need further details please let me know,