When click on 'Found in X User Collections' on an event page, it doesn't expand or redirect anywhere. The collection in this case that it is added to is my public 'attended' collection.

If this is not immediately reproducible I can add any details you require.

An event where the issue occurs:
https://musicbrainz.org/event/eb03d440-be47-479c-bddc-33d88985444f