To reproduce:

1. Make at least one path block by tapping grass with a shovel.
2. Place a bed by tapping on the path block.
3. Observe that the tapped path block turns to dirt and the bed drops as an item.
   I expected that tapping the path block would not make the player try to place the bed (similar to what happens when you tap a snow layer or slab with a bed).

Why? The path block seems to be considered an acceptable block for placing a bed at first, but it has 15/16th block height so placing the bed seems to fail. Since the path block had something placed on it (even though the placement failed), it turned to dirt.

Tested in creative and survival single player on Samsung Galaxy S6 (SM-G920W8), Android 5.1.1 and on Asus B121 Tablet touch & pen enabled, BT keyboard, USB mouse, Win10 Pro x64 10.0.10586 build 10586.