How to reproduce

Create this loot table in a behavior pack

{
   "pools": [
      {
         "rolls": 1.0,
         "entries": [
            {
               "type": "minecraft:item",
               "name": "minecraft:diamond_ore"
            }
         ]
      }
   ]
}

Use /loot to evaluate it

Expected behavior
One diamond ore is dropped

Actual behavior
Content log warning telling you that item must be used instead of minecraft:item

Notes

JE loot tables support both, so this bug makes JE loot tables incompatible in BE but not vice versa (putting aside the dozens of new Java-only loot table features)