Looking at a run in the dynasties tab of rankings and then going to start a new game forces you to begin a new game with the challenge set of the run you most recently looked at (you can of course, close the app, but your shouldn't be forced into that position). This is because the preset challenges upon opening the character select page uses the challenges from the last run you looked at, and if any of those challenges happen to be locked, you can't back out of the character select.
Looking at a run in the dynasties tab of rankings and then going to start a new game forces you to begin a new game with the challenge set of the run you most recently looked at (you can of course, close the app, but your shouldn't be forced into that position). This is because the preset challenges upon opening the character select page uses the challenges from the last run you looked at, and if any of those challenges happen to be locked, you can't back out of the character select.