Kubernetes ingress path regex "or"

I am trying to implement an absolute basic thing from nginx that just seems to be broken in traefik. I must be holding it wrong. My understanding is that we are supposed to use go regexes, and from my testing /(api|docs|redocs) is a valid go regex. Individually (/api, /docs, etc.), I am getting the expected routing behaviour but the regex /(api|docs|redocs) is definitely not working - I'm getting a Bad Gateway.

I haven't found a single example of "x or y" in a Path on the entire interwebs. Please tell me what I'm doing wrong!