Add droplet by API to LoadBalancer return error

I tried this command ( the token and the dropletids has been edited)

curl -X POST
-H “Content-Type: application/json”
-H “Authorization: Bearer aaaaaaaaaaa”
-d ‘{“droplet_ids”: [327455XXX,327455XXX]}’
“https://api.digitalocean.com/v2/load_balancers/a6929bc5-2df6-48d7-a0d1-dc9eb5de5feb/droplets”

But always return {“id”:“unprocessable_entity”,“message”:“only one target identifier (e.g. tag, droplets) can be specified”,“request_id”:“436541b0-7f36-4eb4-8c00-c05fae5c0693”}

I had this code working for more than 2 years but since 2 months doesnt work (I also changed the old token for a new one… with the new token I can create droplets or delete it but not add to the LoadBalancer)