Hi,
I had the some issue - just found the solution (at least for my setup)
As you have guessed it was a formatting problem. I had the following item defined:
Switch Taster_Eco_Auto "Heizungs Modus [MAP(eco.transform):%d]"
after changing it to:
Switch Taster_Eco_Auto "Heizungs Modus [MAP(eco.transform):%s]"
(%s instead of %d)
the rest service displayed the complete item list again.
Hope that helps 
Thomas