Hi Matt, thanks for reaching out.
I can't seem to be able to reproduce your problem without further information. I just tried to match 10 sources from ls_dr8.tractor_s with itself using the x-match web service, and it worked fine. Could you please provide a minimal example, e.g. a CSV table that you are trying to match, and the specific choices for the various fields in the xmatch tool? If you need to provide a CSV file, you can simply email it to datalab@noao.edu , referring to this Helpdesk post. We'll take it from there.
Thank you,
Robert