so i have a zone with 13 location which must be blocked when player is not carrying an item. The zone section works fine. But the barrier doesn't work when i put the zone in location =

But when i put one of the rooms, it works. So am i doing something wrong or is it a bug?

Sounds like a bug. I'll take a look at it.

I wrote this test, and I confirm, it doesn't work. I'll see if I can sort this out today ...

start_at                 = village
locations {
   village : location "You are in a village" ;
   river   : location "You are next to a river" ;
   lake    : location "You are next to the lake" ;
}
objects {
   flippers : object "some flippers" start_at = "village";
   toaster  : object "a toaster"     start_at = "village"  ;
}
connections {
   from, direction, to = [
      village, north, river, 
      village, south, lake, 
   ]
}
zones {
   wet_region : zone {
      locations= [ river, lake ]
   }
}
barriers {
   block_wet_region : block {
      location               = wet_region
      message                = It's too wet to go there. Maybe some make sure you have some flippers?
      block_when_not_carried = flippers
      show_blocked_exit      = false
   }
}