Just a question of curiosity:
Why would you make an HTTPRequest on EventTick?
By any means, try doing the request once, e.g. in BeginPlay. If it never hits the fallback scenario, we would have at least narrowed it down a bit more.
Ok I see you have set it to some Interval actually. However try the request one-time, a branch on Fallback, Breakpoint: Does it not hit even once?
I generally recommend using the both outputs “Successful” and “Failed”/Whatever because “Processing” isnt where I would go in to check anything. The other two nodes on the hand: One should be executed, and thats where we can read the result.