using in-operator in odata 4 filter

Hello community!

I'm trying to filter contacts by unique keys from another system.

Currently, we are using 'eq' and 'or', but that has a limitation (the error states that only 100 nodes are supported in a filter).

After reading the oData 4.01 documentation that is linked in the creatio documentation here https://academy.creatio.com/docs/8.x/dev/development-on-creatio-platform/architecture/development-in-creatio/integrations#title-2088-10, I found the "in" operator, which might bypass this issue completely, so we wouldn't need to page through records.

However, I couldn't get it to run...my filter looks like this:
 

$filter=["QsTbisKey"] in ["47928","50447"]

But it returns an error:

{
    "error": {
        "code": "",
        "message": "An error has occurred.",
        "innererror": {
            "message": "The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; odata.metadata=none'.",
            "type": "",
            "stacktrace": "",
            "internalexception": {
                "message": "Object reference not set to an instance of an object.",
                "type": "",
                "stacktrace": ""
            }
        }
    }
}

I tried using all combinations of other brackets and single quotes but was unsuccessful.

Does anyone know how to do this?

Thanks and BR,

Robert