RESOLVED 6/12/19: OCLC Support was able to correct configuration issues and reload our libraries settings to resolve this issue.
We have had reports from several libraries that the "Request through Interlibrary Loan" button that should display within WorldCat Discovery is no longer visible. This problem seemed to happen sometime between last Friday and early this week.
We are working with OCLC to determine the cause of this problem. Their support and implementation staff are looking into the problem. Updates will be provided when we find out more.