Related field not updating

I have a layout with two portals containing related records. Some records are duplicates so I'm cleaning them up by moving the related records within these pages to the record I wish to keep.

In the top portal the movement of the related record works OK. I cut the record ID out and paste in into the record I wish to keep - so the ID disappears from the duplicate record's portal as expected.

However, the same doesn't happen for the second portal. I cut the ID out and paste it into the record I wish to keep, which works as it shows ID, but it doesn't update the lookup field on that page, and the ID remains in the portal of the duplicate record. If I delete the duplicate record, the moved ID, while the correct ID, still tries to connect to the old missing record.

I've tried clicking in the ID field in the remaining record but it still won't refresh. I've tried refreshing the window. What else can I do to force it to realise its been updated?