HARBINGER SCARABS BROKEN?

I have specced breach legion and harbinger, i used 4 harbinger scarabs in a delirius map to proc 12 harbingers plus the chance at more from the tree..but 12 minimum from the 4 scarabs... the map had 10 harbingers in it.

why does the scarabs state "area contains 3 additional harbingers" if it does not, we can stack 4 of them so their should be at least 12 in the map.

can someone at GGG shed some light on if this is a bug or if the map has a limit of harbinger spawns possible so im not wasting scarabs.

I think there is a hidden cap how much more league content can spawn in your maps.

Last season i was missing sometimes few abysses since i had so many monster and content in my maps. Probably something to do with that.