Reload search analyzers fails "Request body is required"

Really confused why this is happening, local windows install works fine but a fresh install on a linux box, the command through Kibana:

POST /index_name/_reload_search_analyzers

gives

{
"error" : {
"root_cause" : [
{
"type" : "parse_exception",
"reason" : "request body is required"
}
],
"type" : "parse_exception",
"reason" : "request body is required"
},
"status" : 400
}

The exact same index config on a windows install works fine.

Version info:

"version" : {
"number" : "7.6.1",
"build_flavor" : "oss",
"build_type" : "deb",
"build_hash" : "aa751e09be0a5072e8570670309b1f12348f023b",
"build_date" : "2020-02-29T00:15:25.529771Z",
"build_snapshot" : false,
"lucene_version" : "8.4.0",
"minimum_wire_compatibility_version" : "6.8.0",
"minimum_index_compatibility_version" : "6.0.0-beta1"
}

Any help would be great.

oh, not a very helpful error then, I finally found it's not supported in the OSS version as stated here https://www.elastic.co/subscriptions