You could start by rounding up the usual suspects...
First, completely shut down the app. (on the iPad, multi-finger up-swipe, long-press the app-icon on the revealed task-bar, touch the minus-sign) then completely shut down and re-start your device.
Are you using the newest version of irb?
Have you backed-up everything and then removed/reinstalled irb?
If the problem persists, you'll need admin assistance.
Please let us know,
)BOB