Bhagavad Gita, Chapter 7, Verse 25

Veiled by the illusion born of the congress of the Gunas, I am not manifest to all. This deluded world knows Me not, the Unborn, the Immutable.

Not being obvious to everyone doesn't mean something isn't genuinely, fully real.

This names a real, deliberate covering, not an absence. What isn't visible to someone isn't described as nonexistent, it's described as veiled, a real distinction between what's true and what's currently perceived.