Has anyone had this dungeon not load with npcs or loots on the first visit?

No.... but then I normally get into it from North Bastion instead of South.

this game is known to have bugs as such.

certain npc/quest items won't spawn, or can't turn in, if you kind of skip the quest chain-line unknowingly.

the choice is to reload prev save, retry the zone, or skip it for later.

always look up wiki for the zone, and check out the bug section.

If you go in the South entrance there is one NPC and 1 skeleton before you reach the boss. That's it.

I did that one not long ago. There were a couple of skeltons and one vampire, but thats it.

The first time I had a similiar experience but there was loot in the urns and chests, also a enchanted weapon by the vampire. This time nothing, I was thinking there was a quest involved with it but I can't find it, I was thinking it was out of Falkreath but might be misremembering.