Hi, my app (iPhone 6) shuts down instantly when I’m trying to read Volo’s guide. 
All other content seems to work fine.

any ideas on what I can do? 

Did you assign that mobile on your PC's account ??? Did you buy the digital book ??? 

A few things you can try:

• Sign out, then sign back in to the app
• Clear cache and relaunch the app
• Force a manifest download;
  1. Open the sidebar
  2. Select 'My Account'
  3. Tap your profile picture
  4. 'Customer Support' will appear, tap that
  5. Tap 'Download Latest Manifest
  6. This will start the manifest downloading, once it's finished you'll need to restart the app
• Nuclear option; uninstall and reinstall the app

solved!

thank you.