Can't block publishers on some campaigns

I'm trying to block some publisher on a campaign, but even though the API call is successful, the publishers are still not blocked.

This is the request body:

{
"publisher_targeting":{
"type":"EXCLUDE",
"value":[
"investing-placements-24",
"kueez-placements-251",
"9gag-placements-251",
"mobitech-tn-launcher2",
"fronthb",
"rcs-gazzetta",
"mobitech-tn-launcher",
"ume-wangxin-web",
"salesfrontier-elecbean",
"salesfrontier-play2048",
"erowz-coolstreaming",
"lotustechnologies-hirugossip",
"pushpros-health",
"carsandyachts-n",
"omgstudios-doctorreport"
]
}
}

Am I missing something?