I am trying to start writing my own SmartApps and started just using the basic example tutorial but I cannot get the IDE Simulator working in order to test the apps. For example; I’ll click to set a switch active and neither the log generation or state of the test light will change.
I notice that the API is specific to EU/UK so I’m wondering if this is something else that is broken in the UK or is it just me? - have tried in IE and Chrome
https://graph-eu01-euwest1.api.smartthings.com/ide
??
I’ve just had a response on this from support and certainly does appear to be a general issue but they are suggesting a workaround (which means the simulated devices actually show up in your app which isn’t great):
At the moment, we have a work around. This involves creating the devices by: Visiting the IDE website > Click on “My Devices” > “New Device”. From here you can create any device that is needed, along with altering the device type handler to see if this works with your custom SmartApp. Once this has been added, you can implement it in to the simulation you are trying to run.
Once these have been used, we’d advise deleting them from the My Devices screen, as they will populate your application if they aren’t.
I have a similar issue with the simulator. For example I want to use the simulator with a physical device (Nest Thermostat) I select the hub, location etc and then click install - the content in the simulator disappears and theres nothing I can do.
Having no joy with the simulator at all
I’m writing some code which is based on contact sensors so i need a virtual device i can mark open or closed in order test. If i try to use a virtual device i get an error stating simply that ‘the simulator is not running’
Frustrating.
Still simulator doe not work 
Is this seriously still not working on the EU site? Having problems using it. Disappointed…
After some testing in both the US and EU locations I figured out that the default virtual devices doesn’t work. I created as separate TestLocation and added "Simulated " devices to that location. With them I am able to simulate devices and test code.
May I know which location you created.