Help Requested Redirects don't work (and some tips for known XF bugs)

Update broke redirects again.

What I have right now:

Code:

    #Optional - comment out the below rule to do a catchall redirect for any
    #requests for the old /forums/ and just redirect to the new home page /l/
    #RewriteRule ^forums([a-z/.]*) /l/ [R=301,L]
  
    #redirect old member page URLs to new site
    RewriteCond %{QUERY_STRING} ^([0-9]+)(.*)$
    RewriteRule ^forums/member.php$ /l/members/%2\.%1\/? [R=301,L]
  
    #redirect old post URLs to new site
    RewriteCond %{QUERY_STRING} ^([0-9]+)(.*)$
    RewriteRule ^forums/showthread.php$ /l/threads/%2\.%1\/? [R=301,L]

What happens now is a "file not found" message, not even a 404.

Any help is appreciated.