PSO cache not working on 4.24 Vulkan

We’re having an issue on 4.24 Vulkan where our PSO cache isn’t working for some shaders.
We have around 1000 PSOs that are being preloaded, however, several particle systems still hitch upon spawn, and we have confirmed it’s because of a missing PSO.

Nothing has changed related to these assets recently.

Are there any reasons a shader would not be recorded?