I have built the exact same small Weeping Vine farm in 2 locations in the same world and in one build everything works fine, but in the other only two of the dispensers work. Both farms are facing the same direction. I have tried multiple ways of powering the dispensers.

Commenters from my tutorial experience the same issue. It's possible that I'm misunderstanding something about the new redstone changes, but why would it work in one spot and not the other? Flipping the side of the lever/observer clock flips which dispensers work on the broken farms. The direction of the redstone, whether it's an end piece or not, and the power it has do not seem to affect the issue. I can power the dispensers directly with a lever.

I am unable to upload screenshots for whatever reason, so they are here:
https://imgur.com/a/kqEPsyQ