I'm not sure if this is the right place to report this.
For this particular question, whenever I first load it, I get a [Math Processing Error] only for my solution (question displays fine). When I proceed to click the edit button, it displays properly. Saving it then causes the solution to display fine.
I've noticed that the first few Latex display fine, so a possibility is that it doesn't like the \not \equiv code that appears later.
I'm not sure if this happens for anyone else, so I've included a screenshot. (Ugh, I don't know how to load images, so here's the link )
Any reason why it's only occurring for this problem?