Transparent blocks sometimes cause other blocks with transparency properties to visibly disappear, but only from certain angles.
I have included a gif of the effect.
Not sure if this should be engine, since it is likely an effect from the way transparency is implemented, but it could be texture since it only effects things with transparency....
Place a transparent block (eg. Mesh, Glass, Forcefield, etc...) and then place another an arbitrary distance behind it and view. If it is visible, try a different direction. Seems to be only some sides of the blocks.
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The gif (created using the built in gif creator, failed to upload to imgur... here are some screen shots instead.