Setup:
3x3 standard machine casings
3x3 hollow reinforced machine casings with air in the middle
3x3 standard machine casings
An industrial grinder attached to center of a face
Then I right clicked the industrial grinder:

There are only broken textures, messed inventory and the "MISSING MULTIBLOCK" hint.
Test environment: Forge 1816, RebornCore 46, TechReborn 142, together with JEI and other functional mods.

@mezz any ideas?

i have a similar bug like this, but it's not JEI, its the block itself, as u can see in this pic is jei not installed

http://abload.de/img/2016-03-31_17.22.39zdspr.png

http://abload.de/img/2016-03-31_17.22.37m1s9j.png

http://abload.de/img/2016-03-31_17.22.34y5spy.png

http://abload.de/img/2016-03-31_17.22.31wxsl2.png

http://abload.de/img/2016-03-31_17.22.28jssrd.png

ok, thanks for that. It must be an issue with the gui

no problem, i like to help :)

My best guess is that the gui's guiLeft is set to 0, and the texture is being offset to put it in the right place.