Niagara particle is visible despite of alpha = 0


a look at the attribute spritesheet shows that alpha for particles (digits) 1, 2 and 3 is 0, yet I can see the digits at full alpha. This is only for the first 5-7 ms the case.

At 8 ms it’s okay and how it should be:

The material setup should work.

Whats wrong here? A bug?

Thank you,