Just wanted to give the people a heads up who watch this forum and pop into the game.
Currently the Dilithium exchange is emptied of Zen. So if you go in and see the one tab empty that’s why. As soon as any zen is put up to purchase it is gone. Right now the rate is about 500 dil to 1 Zen. You can post dilithium offers and they should sell eventually as people are selling zen. Right now it looks like about a 6 hour to 24 hour sell rate as of this weekend. However the exchange is run on a first in First out rules. So the offers posted prior to yours will get settled first. But as more people try to sell dithium for Zen, the turn around time will increase.
I’m given to understand this happened in Neverwinter, and Cryptic ignored the problem and now the turn around time there is weeks to months from what I have read in the NOP channel. So take that as heresy unless someone who plays Neverwinter wants to chime in. They appear to be trying sorta to avoid this in STO but so far it is more band aid attempt at the moment. I think this caught them by surprise (at least the emptying of the zen completely from the exchange) But that’s what happens when you run a two recruitment events, followed by two only Zen packages that were considered Pretty nice, followed by a Summer sale event. people are spending their zen rather than converting it.
So the short warning is unless you plan to buy zen directly from Cryptic, there isn’t a way to generate it from dilithium on a short notice for impulse buying for anything you want to get with zen.