According to the Neverwinter forums there’s a blockage once again in the game’s external economy, that is the exchange between in-game Astral Diamonds and the ZEN currency that you buy with real money. The discussion thread points at the impending Module 6 as the likely cause as those players with ZEN are hoarding them ahead of the expectation that Module 6 will bring new mounts, companions and packs to buy.
Neverwinter has a dual economy, where an in-game earned currency can be exchanged for a real-money purchased one (In Neverwinter there’s also the third mostly-irrelevant currency of gold coins) via the Zen Astral Exchange (ZAX).
I’ve only bought ZEN using Astral Diamonds once myself, farming a lot of ZEN via Astral Diamond exchange is a time-consuming task if you’re not very knowledgeable about the game’s dungeons and also if your character isn’t very well geared. For much of the time (late 2013 through much of 2014) that I was playing the exchange market was pretty broken – orders to buy ZEN using AD would take a week or longer to fill as there was such demand. The economy did change dramatically in September last year with purchase prices on the Astral Diamond-fed auction house dropping significantly and the ZAX freed up somewhat, however whatever measures Perfect World put in place to ease the exchange economy (either through new AD sinks or banning more bot-players) it seems things have since gotten worse again. This might be a systemic problem or it might be simply market forces at play. It’s an aspect to the game that I find rather interesting to watch even when not actively playing my characters.