Thanks for reporting the issue, grahsand! Just like Rabid, I tried to recreate the situation with Ruins and Curses and City, but it worked as it should.
If you see this happen again, please write down the game number, and post here again with that number.
A bit of explanation: With so many players playing, the *big bugs* that happen all the time and do something completely wrong are usually found immediately. The smaller bugs that maybe happen only while interacting with other cards are also found relatively fast, because there are just so many games played.
But there are also bugs that manifest themselves only if specific circumstances happen and then get strange results (like being reported in the end-of-game screen that you final deck contained -1 Embargo card). If we have game number(s) for those rare events, we can find out what the common situation is, and we can replay the game and vary what's done to see which special play causes the bug.
That's why having the game number is so important to finding the bug, lots of work can be done to help find the root cause.