In some situations, you might encounter an inaccessible collapsed sidebar in Baldur's Gate: Enhanced Edition on iPhone, and you won't be able to use the sidebar buttons.
You can work around this issue and restore the sidebars by activating the Zoom function on your iPhone.
Go into Settings > General > Accessibility > Zoom
A three-finger tap will bring up the zoom window.
A three-finger drag will scroll it down to the bottom of the screen which will allow you to restore the sidebar.