API/Modloader
Forge

Describe the bug
Blue and purple glowshroom blocks are solid blocks. This means that

• Entities can suffocate inside of them,
• They can conduct redstone signals,
• Mobs may be able to spawn on them, if a mod adds a mob that can spawn in the light level 11 the shell gives out,
• A chest can't be opened underneath them, and
• They are susceptible to other behaviours affected by opacity documented on the Minecraft wiki.

To Reproduce

• Point a powered repeater into the side of either glowshroom blockl, and place redstone dust on any other side. The dust becomes powered.
• Place a chest under either glowshroom block, and attempt to open it.
• Use spectator mode to clip your character's head into the block, and enter survival mode. The character suffocates and then enters crawl mode.

Expected behavior
Because they are visually transparent, glowshroom blocks would behave like leaves, ice, glass, and so on, and not conduct redstone, suffocate mobs, etc.

Screenshots/Videos
A glowshroom block conducting redstone.