Embedding Retool as a sidebar app in Zendesk Support

I was following the guide at https://docs.retool.com/docs/embedding-retool to bring a Retool app into Zendesk via their JS SDK.

It mostly works but I'm having trouble passing messages from Retool to Zendesk with parent.postMessage(...) in Retool.

Their SDK creates an iframe so as far as I understand there are now nested iframes after ZAF creates one for my app and a Retool iframe is created inside it.

Would that be a problem or is there another way of doing it?