Identify requires distinct_id even if using Simplified ID Merge API

[RicoTarascio]

Hi!

I've been trying to follow this guide to implement server side tracking. When calling track with event name $identify i get the following error: Mixpanel error: distinct_id, missing or empty

I'm sure $device_id and $user_id parameters are being passed since every other custom event is being tracked and Mixpanel is able to merge profiles correctly.

Is there something that i'm missing? What is the difference between calling and not calling tracking with $identify since merging is working regardless?

Mixpanel Python SDK version: 4.10.1