Fix 2D matrix generator preview update issue

Co-authored-by: DedeHai <6280424+DedeHai@users.noreply.github.com>

wled00/data/settings_2D.htm

@@ -209,6 +209,7 @@ Y:<input id="P${i}Y" name="P${i}Y" type="number" min="0" max="1023" value="0" on
 				Sf[`P${p}S`].checked = d.Sf.PSL.checked;
 			}
 		}
+		UI(); // Update the preview after generating panels
 	}
 
 	function expand(o,i)