So I did a quick search of the forum but didn't see anyone mention this. I just discovered the other day that the buff from Giant's Causeway seems to disappear whenever I upgrade a unit. Then I have to go back and get it again. That's really annoying and inconvenient and largely kills the usefulness of the wonder over the long term, since it's only usable for a temporary period, and as soon as units upgrade it's gone. Is this a bug, or working as intended?