Receiving metrics only from the requested node

Here is my request

curl “x.x.x.x:9600/_opendistro/_performanceanalyzer/metrics?metrics=Heap_Used&agg=avg&dim=MemType&nodes=all”

and the response

{“HlC006EwTASfo9gztqw0Fg”: {“timestamp”: 1606410740000, “data”: {“fields”:[{“name”:“MemType”,“type”:“VARCHAR”},{“name”:“Heap_Used”,“type”:“DOUBLE”}],“records”:[[“Heap”,8.001642112E9],[“NonHeap”,1.90566456E8],[“OldGen”,3.122340352E9],[“PermGen”,1.1183284E8],[“totFullGC”,-2.0],[“totYoungGC”,-2.0]]}}}

Only the metrics from the requested node are returned, although there are 3 nodes in the cluster.
I can do the request for all 3 nodes, from any of the other nodes. I also checked the /tmp/PerformanceAnalyzer.log, no errors or warnings there.
My setup is with docker on 3 different servers.
Can the issue be that I haven’t enabled https on the performance analyzer?

Any clue will be well appreciated.

Thanks and have a nice day,