The input_select entities and the dropdown boxes in general do not open properly in Lovelace interface.
If a dropdown menu is at the bottom of a page, the list tries to expand downwards while there is very little space for that. The interface is almost unusable. Isn’t it possible to have the menu open upwards instead, where is space to display it ?
I am afraid that this is not only iOS-related issue.
I tested the problem on desktop (Chrome, Win10x64) - it really occurs when the input_select control is on the bottom of the page.
This is not actually a bug. I guess this is a behaviour according to the paper-list implementation.