In git main it appears to work but with a warning:

$ guile --r7rs
GNU Guile 3.0.7.13-c1fd55-dirty
...

scheme@(guile-user)> (import (scheme base))
scheme@(guile-user)> (member 'a '(b))
WARNING: (guile-user): imported module (scheme base) overrides core
binding `member'
$1 = #f
scheme@(guile-user)> (member 'a '(b a))
$2 = (a)

-Dale

	-----------------------------------------From: "Arvydas Silanskas" 
To: 48765@debbugs.gnu.org
Cc: 
Sent: Monday May 31 2021 5:10:12PM
Subject: bug#48765: `member` from (scheme base) returns empty list
instead of #f when item is not found

 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