Is your project public? I can diagnose it faster looking at it.

How are you injecting the nrepl middleware/code/libraries/deps into your app so that cider can connect to it?

Finally, assuming you did that right (see https://shadow-cljs.github.io/docs/UsersGuide.html#cider)

I sometimes have to go to the shadow cljs browser tab that has the server info and force a compile, then browser app before it will let me eval something.

The repo's not yet public, I'm afraid. RE: nrepl injection method, how would I go about determining that? I'll go ahead an include the shadow-cljs.edn on the off chance that helps:

{:builds
 {:app {:asset-path "/js"
        :modules {:main {:init-fn app.core/main}}
        :output-dir "public/js"
        :target :browser}
  :cards {:asset-path "/js"
          :modules {:main {:init-fn app.cards/main}}
          :compiler-options {:devcards true}
          :output-dir "public/js"
          :target :browser}
  :test {:ns-regexp "app.cards"
         :output-to "out/test.js"
         :target :node-test}
  :e2e {:ns-regexp "e2e.*"
        :output-to "out/e2e.js"
        :target :node-test}}
 :dependencies [[reagent "0.8.1"]
                [devcards "0.2.6"]]
 :dev-http {4200 "public"}
 :nrepl {:port 3333}
 :source-paths ["src"]}

Check the links above as well as reading the cider docs about shadow, that's a good starting point for understanding. But when you start shadow it needs a cider client lib. Cider Jack in, will add it for you. If you connect, then you have to add it. No way is better, but if emacs/cider adds it for you then the client lib will sync with the server.

I'll do some digging, thanks for the tips

Yeah. After reading that once, feel free to ask again. It's not easy.