Interview scheduling page isn't available error

Summary: A candidate attempting to book an interview is getting the following error: The interview scheduling page isn't available because your job application is no longer active

Content (please ensure you mask any confidential information):

Hi

We have a candidate who has received an email to invite them to interview but when they click on the interview calendar link they get the error 'The interview scheduling page isn't available because your job application is no longer active' (see attached screenshot). However, the job application does appear to have been active at the time. Has anyone ever had this issue and if so, what is causing it?