This is still an issue 15 months later. I've played for months and never noticed it before today because it should only happen if my initial guess is 1 away from the solution. I can refresh the page and make a new guess in the place of the one that is one away. It should be an easy enough to debug.
My best guess is that it gets into an infinite loop when trying to discover what clue to give next. More specifically, since it prioritizes clues like "(x - 500) is a 6th power," it may get into a loop trying to figure out what the highest power is that works. Since 1^n = 1, there's no limit to what power it could be.
The solution is to just special case this scenario and, perhaps, just give away the answer by saying the guess is one away.