It appears that ... ~something~ broke recently:
Maybe some data sources that are loaded client-side are getting blocked by Anubis?
Correction: I let the page opened in a background browser tab and it looks like it actually finished loading after an hour or so. Now the filtering by groups is available again. So it appears that something is just ... very very very slow.
This issue has been migrated to Fedora Forge: https://forge.fedoraproject.org/apps/packager_dashboard/issues/188
Please continue any further discussion there.
Metadata Update from @kparal: - Issue status updated to: Closed (was: Open)