This is the new image format used by iOS starting with iOS 11
So can I not use the app for my photo uploads anymore? Considering I don't use a macbook/laptop anymore this will be quite problematic.
The Box mobile app should support and preview .heic files; we're currently on 4.2.6 and we introduced this in 4.2.4
What's the issue that you're having and do you still experience it with the most up to date app?