Working With Xano and Bravo API issue

I've got a list endpoint working in Xano and in Bravo: but I'm having trouble with a details endpoint.
I can get them both working - but only with different endpoint urls!
Which is confusing. Xano wants to give me an endpoint url of /{id} which returns a 'not a valid integer' error, but the api will return exactly what I want in Bravo if I add $ - so /${id} works on the api endpoint in Bravo. But it means I get a 404 FailedRequestException error in my app.

Any clues or hints in the right direction would be very welcome. 🙂