I am not sure that it is a bug because it seems to be an item that requires movement and thought here is what happens and why. If one player moves only one piece onto the board and runs for the center (dice race) and the opponent moves a piece to that players starting position if the player with only one piece out of start moves his only piece into the center without attacking the blocking piece then he is indeed trapped.
This will always happen.
If the player will hold off moving his only piece off the board he can attack and move through the blocking player as much as he wants.
The reason I believe this is not a bug is that this movement requires strategy of moving and covering start at the same time without this then it really just becomes a foot race with no defense and manouver and thus whoever has best dice wins every time, with this little rule you have to move and attack and always keep an active player in play.
Hope this helps