Visual bug with monostable circuits using target blocks

I noticed that when I build a monostable circuit with a target block like shown in the screenshots, the redstone line to the side of the target block remains visually unpowered. It nonetheless outputs a 1-tick pulse to the lamp.
Steps to reproduce:
1. Build the contraption as shown in the screenshots.
2. Activate the button.
The redstone line which is connected to the lamp will not be visually powered, but the lamp will be activated.