I just tried Wolfram Programming Lab on iPad mini 4 in Safari. Very inconsistent keyboard behavior. With a new notebook open, it took random touching to get a cursor and an open keyboard after selecting the Wolfram Language Input. After getting one cell to evaluate, the keyboard would not stay up. I also could not get the gear icon near the cell bracket to activate. Very strange?
I have been using Wolfram Programming Lab on my MacBook Air in Safari with no problems.