Looks like a regression. Sorry about that.
Fortunately, the compact syntax is still working:
!define ICON1 <img:http://www.eclipse.org/tptp/images/ico_home.gif>
!define ICON2 <img:http://www.eclipse.org/tptp/images/ico_play.gif>
component [Application1 ICON1] as A1
component [Application2 ICON2] as A2
Is it possible for you to switch to this syntax, so that we understand where this regression comes from and that we fix it ?