Dead Ball Appeal

[collinb]

True or False
Runners are permitted to return to a missed base or a base left too soon before a dead-ball appeal can be made?

Is this a trick question? I realize that after all playing action has completed and the defense asked for a dead ball appeal, the umpire calls dead ball. At that point the runners cannot return to a missed base or a base left too soon.
This question came up on a NF test a couple of years ago with IHSA (Illinois),and was marked True