How to recompile Engine shaders?
I looking for the same, I’ve noticed when I adding Reflection Sphere, some shaders still doesn’t reflect it, they need to be recompiled again to be active. I do it by clicking undo/redo and sometimes some glitch resets shaders and it starting to recompile.
Maybe try in the console:
RecompileShaders all # recompiles everything, slow...
RecompileShaders Changed #only recompile changed file
# To clear the cache in case it does not work:
r.InvalidateCachedShaders = 1