The authority search result list fail when more than 20 records show up and multiple pages scroll down the search. The same behavior was reported on bug 17048, Iming Chan explained much better with screen shots attached to bug. I've been tested in Koha 18.05.04.000 in production and in Koha demo powered by Orex Digital with the same version. Only tested in Koha configurated with Zebra (2.0.59)
*** This bug has been marked as a duplicate of bug 21405 ***