Issue when removing one of two ads

I think I found a bug when removing a house ad. I had ad1 and ad2 defined as house ads to display an image with some simple HTML, and they were selected for “Between topics”. But then I deleted ad1 from the list of available house ads, and that appears to have made it automatically disappear from the “Between topics”. But it acts as though it’s still expecting ad1 to exist, because it started randomly sometimes not showing any ad in the topic list after the defined number of N posts. Then I re-created ad1 by copying the HTML from ad2 into it and it re-appeared in the “Between topics” selection, and everything is back to normal.