Pressing 1 to go back to Place mode after deleting something, places the last thing you had on your cursor. The problem with this, is that whatever was last on cursor is invisible so you cannot line it up properly. The only solution is to manually click on Place to return to 'place mode'.

Also, I realise it's early access, but I think the prop menu is one of the biggest limiting factors in building. It takes too long to navigate and it's too easy to misclick. A Tabbed window on the right side would improve workflow massively, and I think kids would have an easiler time too.