Warden won't spawn when a sculk Shrieker is on top of a tower of carpets

I tried placing a bunch of carpets on top of each other and then I put a shrieker on top of one carpet ("can_summon" block state is set to "true" via debug stick) 

What I expected to happen was...:
A warden would emerge after 3 shrieks

What actually happened was...:
The warden did not spawn, instead played the "warden takes notice angrily" sound after shrieking.

Steps to Reproduce:{}

1. Make sure the game rule "doWardenSpawning" is set to "true"
2. Put a tower of carpets down (like so in my screenshot)
3. Place a sculk shrieker
4. Use the debug stick to change the "can_summon" block state to "true"
5. Make the shrieker shriek 3 times, then step on the shrieker again
6. Listen for the "warden takes notice angrily" sound.