I've found this bug in FTB Infinity Evolved 1.6.1 (Mc1.7.10) by using the Portal Gun to move a glass block on top of an energy pylon.
What happens: It forms an functional energy Pylon + core, but when you right click the energy core to change the transmit direction, it turns into an Draconic Block

Hope you understand

Flo.

Are you on a server? And if so are you running a plugin system like cauldron/thermos etc.

I've tested this on my own server (standard FTB Infinity 1.6.1 config) and in Single Player. (Haven't found a plugins folder or something)

The only differences is that on a Server the block automatically turns into an Draconic Block without right clicking it.

If you need something tell me.