Pro tip, if this happens to you split your tickets up into smaller chunks! It has two effects:
One is that you will see progress from one sprint to the next, even if it’s 1 story point at a time.
It also has a psychological effect! If you’re like me you will avoid the huge, nebulous tasks. But if it’s something manageable with a defined start and end, you will do it. You could probably even schedule it.
Yeah holy shit! I hope this is a made up example. A six month sprint where you change literally everything about your UI? No wonder customers are upset!