Can't pull mirror from public GitHub repo to private GitLab repo on gitlab.com bronze plan

From reading the forums, I gather that there was somewhat of a dustup and/or lingering problems with pul mirroring. TBH, at this point I am confused as to what’s supposed to work, but GitLab docs seem to be pointing in the direction of “pull mirroring on gitlab.com requires Bronze plan”.

However, I am unable to get this to work. I am on a Bronze plan and I have a private repo on gitlab.com. In Setting > Repository > Mirroring, the “mirror direction” popup is disabled.

What gives? Should this work? (I want to mirror a public GitHub repo, in case that matters.)