Furnace placed facing West or North emit fire particles from the back instead of the front

When cooking in a furnace, the fire particles come out of the back instead of the front.

Depending on what direction the furnace is facing, flame particles will show though the back instead of the front.

Steps to reproduce

• Place down 4 furnaces facing north, south, east and west.
• Smelt something in all 4 furnaces.
• Observe that 2 of the furnaces show fire particles coming from the back.