writeable /afs bind mount inside a podman container

Hi all,
  I'm using podman to run a container with a non-root user ("rootless") and trying to bind mount /afs into the container such that it is writeable.
  The user already has tokens, so in principle processes in container can write to the bind mounted /afs inside the container.  Instead inside the container /afs appears to be writeable, but any attempts to write result in "Permission denied".
  In fact, using apptainer to create a container from the same image and bind mounting /afs into the container does result in a writeable /afs, so I know it's possible!  (I've thought of switching to apptainer instead of podman, but it has other problems.)

If anyone has gotten this to work let me know!
C.