Quick answer: Unity Animator CrossFade with 0.0 duration instant but expected? Yes, 0.0 is instant; for a snap, that's correct - if you want any blend, use 0.01+.
Cross-fade to a different state for stagger animation; reading expects smooth blend, code says 0.0; instant.
Use small positive duration
0.05 to 0.15 is invisible-but-not-instant. Smoothness preserved.
Or use SnapTo
For deliberate instant transitions, explicit SnapTo. Clear intent.
Audit CrossFade calls
Each call's duration value. 0.0 should be intentional; not accidental.
“CrossFade duration is direct. 0.0 = instant.”
Document the 'minimum blend duration' for your project. Engineers pick from a small set; instants are deliberate.