Redstone dust connected to dust down and to the side does not activate blocks in that direction when it is powered from below

Steps to reproduce

1. Build the layout shown below.

   hopper	redstone dust
   redstone dust	solid block B
   solid block A

2. Power the dust on top of solid block B, for example with a redstone torch to the right of it or with a lever on solid block B.
3. Drop an item on the hopper.
4. Power solid block A, for example with a redstone torch below it or a lever on it.
5. Break the power source placed/activated in step 2.

Expected result

The item stays on top of the hopper because the redstone dust on top of solid block B remains powered and pointed into the hopper.

Observed result

The hopper collects the item. It is no longer locked by the powered redstone dust that points into it.