My Gems and Lingots are all Going Down the Drain!!!
On my Duolingo mobile account, I bought the health shield for 500 gems. Little did I know that it is a piece of junk. I had run out of health points and the shield could give me unlimited health points so I wouldn't have to limit myself to 5 mistakes per 25 hours (which I personally think is ridiculous in the first place). When I went back onto a lesson, it said that I didn't have any health points and denied me access to the lesson!!
Please, throw away your IOS mobile device and use a PC with a web browser like Firefox, Chrome where you can train typing, instead of tapping word bricks.
The www.duolingo.com full desktop website does not use health or requires shields.
Same will probably true for the mobile compact browser view, when you access the Duo website from your IOS device.
You could also test the Android app, if you are affected there on A/B beta health tests or not (usually not) on an Android emulator.
Health might be related to your Duo account, not IOS!
But in most cases the IOS app - their lovely A/B testing plattform - is what creates all the trouble.