I am trying to filter out Guest users in my Graph query. Since the ne comparison operator is not supported I was trying $filter=userType eq 'Member' or userType eq null instead. That fails too though. Any known workarounds to list users with null as userType?

Without that I need to download about a million rows each time and throw 4 out of 5 away on the client side, which is pretty slow and wasteful.

{
"error": {
    "code": "Request_UnsupportedQuery",
    "message": "Unsupported or invalid query filter clause specified for property 'userType' of resource 'User'.",
    "innerError": {
        "request-id": "411f7927-c3af-4042-a619-eee1c88971a0",
        "date": "2018-03-17T18:28:35"
    }
}

Update as of June 2021

the ne comparison operator is now supported on userType on graph! So you can now get users that are not guest users with this query: https://graph.microsoft.com/v1.0/users/$count?$filter=userType ne 'guest'

here is a link to graph explorer with that query