I see no such issue here:
The sky reflections are whiter with the PBR setting, but this is because it got broken, fixed clouds... So it's "normal" (i.e. it does correspond to the clouds coverage).
Maybe you got a driver issue, somehow... Sometimes, the reflection probes fail to "start" (I saw this happening under Windows, never under Linux) on login, and you need to switch the reflections settings to kick them up...