Missing messages despite debug logs showing responses

[mrhockeymonkey]

Environment

server: sentry on-prem 21.8.0
crate: sentry = "0.34.0"

Steps to Reproduce

I have a small application tailing logs and forwarding errors to sentry.

    if matches!(sentry_level, sentry::Level::Warning | sentry::Level::Error | sentry::Level::Fatal) {
        sentry::capture_message(&log.message(), sentry_level);
    }

This works fine if using sentry.io but messages do not appear on our on-prem sentry server.

Enabling debug in config only yields these messages

[sentry] Get response: `{"id":"c234eb164ff441d4810167b70dc29eab"}`
[sentry] Get response: `{"id":"b95c6f72d0114fca9c95a348ae4ce5fd"}`

Full code here: https://github.com/mrhockeymonkey/consul-beat/tree/main/consulbeat

Expected Result

Log message should appear in the UI as they do when using sentry.io.

Actual Result

No activity is seen in the UI

Is there anything else I can debug in this scenario? The readme says "should work with on-prem Sentry versions 20.6 and later", I hope that's still the case or was there some breaking change added?