Spawn rotation inverts past 90 degrees

Hi everyone

I have a peculiar situation. I am spawning an actor and setting the pitch rotation at spawn:

However when I inspect the actor at runtime, it has flipped the rotation:

I did some experimenting and I found that if I specify <90 for the spawn pitch it retains the correct values:

But as soon as I go over 90 it flips the axes (this is spawning with pitch=91):

It’s frustrating me cause I want the lerp the pitch from the initial value back to 0, but depending on the spawn pitch, the initial value is not retained so I can’t create a predictable timeline value.