We have a similar problem at Oxford Scholarship Online as in T256757, namely that we're missing some URL patterns in the EZProxy configuration.

At https://www-oxfordscholarship-com.wikipedialibrary.idm.oclc.org/, searching in the text box takes the user to the not-proxied URL https://www.universitypressscholarship.com/search?isQuickSearch=true&pageSize=20&q=test&sort=relevance#

We're using the OCLC provided stanza (https://github.com/WikipediaLibrary/twlight_ezproxy/blob/master/ezproxy.cfg#L116) but it looks like we might need to also be using the one for University Press Scholarship.