From the IASSIST workshop:

"The stacks just disappeared after clicking launch. One of the participants said they saw an out of resources error I did not see. I tried and it disappeared for me too. No error. The multiple iCat's were due to disappearing stacks. I know it is odd but I saw it happen."

Looking at the backend (ndslabsctl list stacks, kubectl get pods --all-namespaces), I see multiple iCAT stacks running for the workshop participants. So, for some reason the stacks were not displaying back to the browser.

I don't have a repeatable test case yet. I've installed Apple's Network Link Conditioner to try and simulate a bad network, but so far I can't repeat this problem in Chrome, Mozilla, or Safari (on Mac). It might be worth considering what would cause the stack to "disappear".