Please read the message below from Amplify regarding updating to iOS8:
At this time we currently recommend that customers remain on iOS 7, and recommend against moving forward with upgrading to iOS 8. While we have made improvements to our experience on Safari under iOS 8, there remain issues that impact the usability of certain activities. Additionally, as witnessed by the recent release and pull back of iOS 8.0.1, Apple is continuing to work on fixing stability and functional issues within iOS 8 that may impact our product.
For customers who have updated their devices to iOS 8 we fully support Chrome under iOS 8, and that may be used as a valid workaround until we fully support Safari under iOS 8. If an iPad has been updated to iOS 8 the key areas in which usability is affected in Safari are short answer activities, copying text from a reading excerpt activity, and writing activities.
We are continuing to work diligently on a fix for these issue and will have an update on a timeframe for resolution within the next week.