Cannot create Hide/Reveal Mask using iPad

The Hide/Reveal Mask works fine on my PC at work.  But I cannot seem to find a way draw hide/reveal areas (either rectangles or polygons) on my iPad.  Not using the touch screen, nor with a connected trackpad. I use the iPad at the game table, not a PC, so the Hide/Reveal Mask is not much use to me if I cannot control it with the iPad. Am I missing something?  Is there some trick to getting this to work on an iPad (using the default Safari browser)?

Running into this exact same issue. Planning to DM using R20 in person and an ipad as my DM control, but not having access to basic fog of war controls is a deal breaker. If there's no solution here I may need to look into other tools. Also I am using chrome, so doesn't seem to be browser specific. Tried using a bluetooth mouse which in theory would be the same as PC and nothing. As a more positive note, the spell effects with the stylus are so fun to play with