Logstash mutate copy field not available in filter scope?

Question

I'd like to access a field that was copied in my filter block, however it appears the value isn't set at that point, or that I can't access it.

When the same conditional logic is in my output block it works as expected.

Sample of the "json" field after the json filter block. The original input message contains a "message" field that is correctly parsed as shown below.

{
"json":
    {
        "groups":
        [
            "vdos.all.hosts.virtualmachine",
            "vdos.all.compute.all"
        ],
        "itemid": 1632807,
        "name": "Memory Guest Usage Percentage[\"X001\"]",
        "clock": 1642625307,
        "ns": 723739588,
        "value": 4.992676,
        "type": 0
    }
}

Logstash config

filter {
        json {
                source => "message"
                target => "json"
        }
        mutate {
                copy => { "[json][groups]" => "host_groups" }
        }
        if "vdos.all.compute.all" not in "%{[host_groups]}" {
                drop {}
        }
}

I've tried

if "vdos.all.compute.all" not in "[host_groups]" {
    drop {}
}

as well as trying to access the json field directly.

if "vdos.all.compute.all" not in "[json][groups]" {
    drop {}
}