Ctrl-X Ctrl-S not working for REPL defined defn's

[naxels]

When I define a function at the REPL, I get the autocomplete as well as the function/argument after pressing spacebar after the invocation of the function.

I can also do Ctrl-X Ctrl-D for the doc.

However when trying to do Ctrl-X Ctrl-S, nothing shows up

Example:

Define in the REPL:
user=> (def visitors (atom #{}))
user=> (defn hello
#_=> [username]
#_=> (swap! visitors conj username)
#_=> (str "Hello, " username))

After this type:
user=> (hello

now when you press spacebar you will see the argument required
or when you press Ctrl-X Ctrl-D you will see the doc

however when Ctrl-X Ctrl-S, nothing appears.

Is there something I'm missing?

Thank you,
Patrick