The same thing happens to me since yesterday.
Specifically, the game CRASHES when I open the GEM STORE, however the Trading Post and Gem Exchange are totally fine.
Here are some of the things I did right before this started to happen, maybe one of these is the cause for the crashes, in order :
I let GeForce Experience update my drivers
I activated gem codes ingame (the gem store worked fine then)
I bought a few home instance upgrades on the gem store (the gem store worked just fine until this very moment)
One of these might be the culprit (or none, who knows).
If anyone who is experiencing the same issue did any of these three right before it started happening, it might help the devs to find and fix the problem.