This acacia plank bug is a really odd phenomenon, and this doesn't occur within other wooden planks.  Stairs, slabs, fences etc all have their usual bright orange however the planks appear grey. Frustrating for mapping out my acacia structures.

As shown in the images below, other structures are built with slabs and stairs and fences (appear orange). However the building in the bottom left corner appears grey (with a strip of orange stairs).