it does actually appear this would be the problem as we're using the netty engine and the trace ID is set in a thread local

hey @John Peña, i'm not familiar with opencensus, but if it works like opentracing then yes the trace id is stored as a thread local so is broken by coroutines ( as they can change thread). To solve this you need to store trace context in the coroutine context ( using a thread context element for ex ) . Take a look at this for ktor; https://github.com/zopaUK/ktor-opentracing