This is because there is a change in the font family. It is now either "Font APEX Small" or "Font APEX Large"
Modify your css to get it work.
Icon support is already available for textfield item type, You can just place the required icon class in the "Appearance=>Icon".
"Font APEX Small" should work fine.
Thank you Dharmendra,
font-family: "Font Apex Small"!important;