EBS 12.2.6: Auto Refresh in Requests form does not work

We are in the process of upgrading from EBS 12.2.5 to 12.2.6. The latter introduced a new function on the view concurrent requests form: Auto Refresh. When the box is checked, the requests screen is supposed to be refreshed automatically. We had applied the same patches (21900901 and its prerequisites) to different test instances. In one the Auto Refresh function works as expected, in this other the screen stays static with no auto refresh even though the box was checked.

Any idea how to make it work consistently?

Thanks in advance.