When I try to summon a million of Piglins with the "/summon Piglin" command on a repeater command block, and set to always active, it won't summon Piglins or any nether mob in the nether.

How to reproduce :

1. Go in the nether.
2. Place down a repeating command block.
3. set the command block into always active.
4. write "summon Piglin" in the command slot.
5. Exit the command screen, and no piglins will appear by the command block.

If it works for you, put down a comment.

PS: If you have trouble with the infinite summoning, put another repeating command block and set it to always active, and type : "kill @e". Make sure you're on creative.