Can't click sign as block

[sdawd2q3e]

When editing a point, I cannot select a sign as the block for the clickblock point type.

EDIT: sign's on a wall can't be selected. Signs standing in a field (i.e. with a post) can.
EDIT 2: further testing, I can click an oak sign, but not a dark oak sign. An oak sign on the wall still can't be clicked.

The problem
According to the spigotmc website - "Click block - Proceed after clicking a block (can be a sign)."

When issuing the setblock command, it will not provide a confirmation unless you click something besides a sign.

Steps to Reproduce
1.Create Tutorial
2.Create Point
3.Edit point with setblock command
4.try and click a sign