contagious rot in Cattleya new growth

[Oranagra]

Hi.
recently i noticed that many of my Cattleyas have some kinda of infection in their youngest growth.
I'm cutting into clean tissue and applying cinnamon, but it keeps happening to the next growth, of several plants.
(I'm very careful, and i'm quite sure i didn't drip water on these when they sprouted)

sometimes it is clear from the start that the new knob has some dark spots on it, and is not solid green, when it grows one of the sheaths turns black, and soft.

other times, it starts from the very tip of a newest growth that is nearly mature, and slowly spreads downwards.