Default `member` works fine:
$ guile
> (member 'a '(b))
$1 = #f
However, using scheme base it returns empty list
$ guile --r7rs
> (import (scheme base))
> (member 'a '(b))
$1 = ()
Other functions (memq, memv) seem to work fine.
I am using version 3.0.5 as distributed by debian bullseye