Category is missing from outlook event from the notification - events

Question

I had set up graph client notification for event updates, when I add a category to an existing event, the updated event from notification is missing the applied category sometimes. I tried to get the event at some intervals and found out that the category does show up but there is no definite time delay, does anyone know what could be the max delay or any technique to get the category immediately?
Code used to subscribe for notifications.
POST https://graph.microsoft.com/v1.0/subscriptions
Content-Type: application/json
{
"changeType": "created,updated",
"notificationUrl": "https://webhook.azurewebsites.net/notificationClient",
"resource": "/users/{userId}/mailfolders('inbox')/events",
"expirationDateTime": "2016-03-20T11:00:00.0000000Z",
"clientState": "abcd"
}
Received notification on updating an event (Added a new category to event)
{
"changeType": "updated",
"clientState": "abc",
"resource": "Users/{UserId}/Events/AAMkAGJjMGZiYmVmLTdkNzctNDFjMy05MDdmLTQ5MzM1NWZjZWVhZQBGAAAAAACcxCFvSYx4Qq2TvvDk7ptoBwApGtasXg2jRLv-yfVbSS5rAAAAAAENAAApGtasXg2jRLv-yfVbSS5rAAE3GB9UAAA=",
"subscriptionExpirationDateTime": "2022-02-09T00:07:27.333244-08:00",
"subscriptionId": "00508233-d60c-4905-8c4f-cb101a43f8c1",
"resourceData": {
"id": "AAMkAGJjMGZiYmVmLTdkNzctNDFjMy05MDdmLTQ5MzM1NWZjZWVhZQBGAAAAAACcxCFvSYx4Qq2TvvDk7ptoBwApGtasXg2jRLv-yfVbSS5rAAAAAAENAAApGtasXg2jRLv-yfVbSS5rAAE3GB9UAAA=",
"#odata.etag": "W/\"DwAAABYAAAApGtasXg2jRLv/yfVbSS5rAAE4W5d/\"",
"#odata.id": "Users/bfc9acdc-7ae7-4cbe-af4f-843acd8945d8/Events/AAMkAGJjMGZiYmVmLTdkNzctNDFjMy05MDdmLTQ5MzM1NWZjZWVhZQBGAAAAAACcxCFvSYx4Qq2TvvDk7ptoBwApGtasXg2jRLv-yfVbSS5rAAAAAAENAAApGtasXg2jRLv-yfVbSS5rAAE3GB9UAAA=",
"#odata.type": "#Microsoft.Graph.Event"
}
}
When I tried to get the event from graph client the category was missing in the category list
{
"allowNewTimeProposals": true,
"attendees": [],
"body": {
"content": "",
"contentType": "html",
"#odata.type": "microsoft.graph.itemBody"
},
"bodyPreview": "",
"end": {
"dateTime": "2022-01-23T03:30:00.0000000",
"timeZone": "UTC",
"#odata.type": "microsoft.graph.dateTimeTimeZone"
},
"hasAttachments": false,
"hideAttendees": false,
"iCalUId": "040000008200E00074C5B7101A82E00800000000FA8C485E1718D8010000000000000000100000002019A4F391D06D40B7A90ACC0E408951",
"importance": "normal",
"isAllDay": false,
"isCancelled": false,
"isDraft": false,
"isOnlineMeeting": false,
"isOrganizer": true,
"isReminderOn": true,
"location": {
"displayName": "ABCD",
"locationType": "default",
"uniqueId": "ABCD",
"uniqueIdType": "private",
"#odata.type": "microsoft.graph.location"
},
"locations": [
{
"displayName": "ABCD",
"locationType": "default",
"uniqueId": "ABCD",
"uniqueIdType": "private",
"#odata.type": "microsoft.graph.location"
}
],
"onlineMeetingProvider": "unknown",
"organizer": {
"emailAddress": {
"address": "{userEmail}",
"name": "{Name}",
"#odata.type": "microsoft.graph.emailAddress"
},
"#odata.type": "microsoft.graph.recipient"
},
"originalEndTimeZone": "Sri Lanka Standard Time",
"originalStartTimeZone": "Sri Lanka Standard Time",
"reminderMinutesBeforeStart": 15,
"responseRequested": true,
"responseStatus": {
"response": "organizer",
"time": "0001-01-01T00:00:00+00:00",
"#odata.type": "microsoft.graph.responseStatus"
},
"sensitivity": "normal",
"showAs": "busy",
"start": {
"dateTime": "2022-01-23T03:00:00.0000000",
"timeZone": "UTC",
"#odata.type": "microsoft.graph.dateTimeTimeZone"
},
"subject": "Test1234",
"transactionId": "BFA967CF-A111-5A49-8564-C74031DEA04B_6F9F0BA5-05C8-465F-9B56-5E3318BFF06B_343",
"type": "singleInstance",
"webLink": "https://outlook.office365.com/owa/?itemid=AAMkAGJjMGZiYmVmLTdkNzctNDFjMy05MDdmLTQ5MzM1NWZjZWVhZQBGAAAAAACcxCFvSYx4Qq2TvvDk7ptoBwApGtasXg2jRLv%2FyfVbSS5rAAAAAAENAAApGtasXg2jRLv%2FyfVbSS5rAAE0tLDTAAA%3D&exvsurl=1&path=/calendar/item",
"categories": [],
"changeKey": "KRrWrF4No0S7/8n1W0kuawABNJg+hw==",
"createdDateTime": "2022-02-02T09:29:25.2557072+00:00",
"lastModifiedDateTime": "2022-02-02T09:37:47.6734052+00:00",
"id": "AAMkAGJjMGZiYmVmLTdkNzctNDFjMy05MDdmLTQ5MzM1NWZjZWVhZQBGAAAAAACcxCFvSYx4Qq2TvvDk7ptoBwApGtasXg2jRLv-yfVbSS5rAAAAAAENAAApGtasXg2jRLv-yfVbSS5rAAE0tLDTAAA=",
"#odata.type": "microsoft.graph.event",
"#odata.context": "https://graph.microsoft.com/v1.0/$metadata#users('{userId}')/events/$entity",
"#odata.etag": "W/\"KRrWrF4No0S7/8n1W0kuawABNJg+hw==\"",
"occurrenceId": null,
"calendar#odata.associationLink": "https://graph.microsoft.com/v1.0/users('{userId}')/calendars('AAMkAGJjMGZiYmVmLTdkNzctNDFjMy05MDdmLTQ5MzM1NWZjZWVhZQAuAAAAAACcxCFvSYx4Qq2TvvDk7ptoAQApGtasXg2jRLv-yfVbSS5rAAAAAAENAAA=')/$ref",
"calendar#odata.navigationLink": "https://graph.microsoft.com/v1.0/users('userId')/calendars('AAMkAGJjMGZiYmVmLTdkNzctNDFjMy05MDdmLTQ5MzM1NWZjZWVhZQAuAAAAAACcxCFvSYx4Qq2TvvDk7ptoAQApGtasXg2jRLv-yfVbSS5rAAAAAAENAAA=')",
"responseHeaders": {
"cache-Control": ["private"],
"transfer-Encoding": ["chunked"],
"vary": ["Accept-Encoding"],
"strict-Transport-Security": ["max-age=31536000"],
"request-id": ["110a7a40-540d-46d2-9687-a50ea7994ab9"],
"client-request-id": ["110a7a40-540d-46d2-9687-a50ea7994ab9"],
"x-ms-ags-diagnostic": [
"{\"ServerInfo\":{\"DataCenter\":\"South India\",\"Slice\":\"E\",\"Ring\":\"2\",\"ScaleUnit\":\"000\",\"RoleInstance\":\"MA1PEPF00002512\"}}"
],
"date": ["Wed, 02 Feb 2022 09:37:50 GMT"]
},
"statusCode": "OK"
}