Timezone shows UTC in Outlook when created by graph api - outlook

Question

When creating an calendar event via MS Graph API the event looks different in the OWA and the Outlook Client.
In the Outlook client the event shows up ok in the overview, but when looking at the details it is shown in UTC instead of my timezone (Western Europe) and I cannot click/unclick the timezone button. If I open the same event in OWA it shows up in the correct timezone. Also if I send the event to another organisation it also shows up ok.
This leads me to believe it's something in our outlook client, but then I cannot see any difference in the graph API between events created from Outlook directly (looks ok) and the ones created via a rest call.
This is my payload
{
"subject": "tEST",
"organizer": {
"emailaddress": {
"address": "<email>"
}
},
"start": {
"dateTime": "2019-10-09T08:01:00.0000000",
"timeZone": "UTC"
},
"end": {
"dateTime": "2019-10-09T09:01:00.0000000",
"timeZone": "UTC"
},
"attendees": [
{
"emailAddress": {
"name": "Mattias Johansson",
"address": "<email>"
},
"type": "optional"
}
],
"reminderminutesbeforestart": 15
}
and this is a screenshot of the booking, the time is slightly different since it's another booking than the payload.