After having been updated to Koha 3.10 last night, we are getting "no results found" when searching authorities through the authority module. We also noticed that when editing MARC records, subfield 9 is blank for some authors we know to be well established in our database. And when there is a MARC 100 subfield 9 listed, clicking on the gadget to check the authority, yields a "no results found" message.
I can search authorities just fine in 3.10.x, so I suspect this is more of a support question than a bug in Koha. If the problem is still happening I suggest raising the question on the mailing list, on the Koha IRC channel, or with a Koha support provider.