TL;DR
When in map mode, entities should be always placed as ghosts even if you have the item in your inventory.What ?
I did check this collection (viewtopic.php?f=80&t=45635), but it looks like this is missing.ATM, when you are in map mode, if you have an item in your inventory you have to press SHIFT to place it as a ghost.
While this make sene when playing directly with your engineer, it does less so when you are using the map/radar, because it's implicit that you are operating at another scale or you are planning.
When in map mode, entities should be always placed as ghosts (and maybe press SHIFT TO INVERT the process and place from inventory)