As seen in this video redstone burnout clocks don't make the sizzle sound when they are initially created. The sound will only happen whenever the already existing clock is updated in some way.

Steps to reproduce:

1. Place 2 blocks facing upwards diagonally
2. On the lower block place a redstone dust and to its side covered by the top block place a redstone torch. Notice that redstone torch didn't sizzle when it burn out
3. Now place a lever next to the redstone torch and power it on. Redstone torch did sizzle

Expected result:
Redstone torches always sizzle when they burn out.

Observed result:
Redstone torches sizzle only when the redstone torch burnout clock is activated by lever.