The path turns to dirt if a slab at the top of the block is placed above it

The trail turns to dirt if a any slab at the top of the block is placed above it
Steps to reproduce:
Place any slab above the trail that is located at the top of the block
Observed results:
The path turns to dirt, although there is no logical reason for this
Expected results:
The block of a path over which there is a slab