Rendering of drive fixtures is buggy

Describe the bug
When filling drive fixtures with storage cells, they are rendered incurrectly. Sometimes, filled fixtures appear empty, but most of the time their texture is just broken

Here, you can just see through the LEDs on some of the drives:
http://prntscr.com/n48eaw
http://prntscr.com/n48ex1
http://prntscr.com/n48f5j

This fixture is actually filled with cells, but appears empty:
http://prntscr.com/n48fka

Adding/Removing drives to/from one fixture often affects the rendering of others on the same network.

To Reproduce
Add drive fixtures to a network and place drives in them.

Environment
FTB Revelation 2.7.0

• Minecraft Version:
• AE2 Version: rv6-stable-6
• Forge Version: 14.23.6.2796

Drive fixtures are provided by extracells, not AE2 itself.

oh, sorry - i have opened an issue there