Just want to chime in here and say I had the same problem, and as I'm using it for free it was particularly infuriating since I didn't know what was going wrong and I wasn't able to re-try different inputs. I work at a university and it wouldn't be a big deal for my lab to subscribe me to the Pro service but I certainly can't do that as long as this doesn't work. I note though that if you reveal one step at a time, it will show most of the steps, but when you hit one near the end, then suddenly everything gets blacked out (I want to see those steps though!). My input to produce this was
y''(t) + a*y'(t) + b*y(t) = x(t)
NB, this equation did not have a problem:
y''(t) + a*y'(t) + y(t) = x(t)
The bug appears to arise where the pathways for solving these two equations diverge.
