FOSS gamedev and creative worlds

Hi !
I'm back on Minetest !
I just have a question :
I played my map Fort Boyard with Minetest 0.4.15 but i have a problem... Iron Bars don't want to be connected with blocs !
I mean, in a corner. So my treasure room have a long hole between the iron bar and the wall.
I just can't let them like this! Is anyone thought about my tigers? They can hurt someone !

Seriously, how can i do to fix them ( make them as they were on 0.4.14)
( and optionaly, is anyone know how to make them stand "in front of a block" (like doors)

Thanks :)

I don`t know why it is so, but it seems so is done on default in MineTest.(I checked, i have, too)
Connected with blocks can only glass panes