Has anyone else had the issue of customers getting an error on the app that tells them the "item can't be added to their cart at this time"?
Lots of your items are in people's carts. Advise them to try a browser instead.
@KylasKosmos : If you look through this forum, you'll see that there are innumerable threads about issues with the Etsy apps. Since there do not appear to be any workarounds for this problem, NanaLetha's suggestion is probably the best "solution". Also there appear to be fewer issues with a desktop browser than a mobile browser.
The buyer may be using an older version. Have them update the app. Uninstall and reinstall.
The other issue may be their phone. Some phones may not be able to handle the updated version of the app.