Cannot select an employee on change assignment page

Summary:

Cannot select an employee on change assignment page

Content (please ensure you mask any confidential information):

We enabled this page a few weeks back, and I could search and narrow down lists of employees by searching.

However I noticed today that even though I can search the names still, I can't actually narrow down the search or even select a name to navigate to the next page?

In this example I have searched for Warren Harrison, but I cant select his name or enter to navigate to the net page?

Any suggestions what has changed as this worked before?