I am on the road today but wanted to quickly share some good news that with today’s Fly Delta App update the issue with off-line mode seems fixed!
I have had the privilege of beta testing this update and all is working very well now other than screen changes are a tiny bit sluggish but will take that over an unusable app.
Well done for this fix Delta – well done! – René
Never was an issue for me with the iOS version but I have heard about the offline problem on android devices. (Definitely not trying to argue iOS vs Android, they both have their virtues.)