Anyone having issue when you phone keyboard?

If you are talking about challenges, then yes, you cannot enter any capital letter in it. It will be automatically lower cased.

In the lessons and the challenges I think that all entries are converted to lowercase. Or at least that has been my experience. In some cases it can cause confusion or errors, but I think they do it to make it more accessible (it's hard to write in some mobile devices).

Thanks for the information! The answer that I need to submitted was different than I thought.