I ran into something similar a while back. It might be the map you have selected. Some of them, especially the smaller ones don't have a 'back' or a 'middle', so when something is put in one of those zones it gets bumped to what ever does exist. IIRC they added a feature to the map selector which has the placement locations marked and coloured according to zone so you should be able to check easily.
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"Will whiskey help? Let's find out." -- Brian Kantor
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"Will whiskey help? Let's find out." -- Brian Kantor