parse-server: Queries with Parse.Promise.when cause "Request timeout"

There are a couple places in our app where we do things in parallel with Parse.Promise.when(), they worked in the Hosted Parse, but not anymore after migration. Is it supported?

Here’s the general structure of those cloud functions:

var promises = [];

var query1 = new Parse.Query("Class1");
query1.equalTo("checked",false);
promises.push(query1.find());

var query2 = new Parse.Query("Class2");
query2.containedIn("name",["foo","bar"]);
promises.push(query2.find());

Parse.Promise.when(promises).then(function(results1,results2){
    // process results and return to client
}, function(error){
    // handle error
})

Server log when these functions are called: at=error code=H12 desc="Request timeout" method=POST path="/parse/functions/myfunction" host=host request_id=123456 fwd="1.2.3.4" dyno=web.1 connect=1ms service=30001ms status=503 bytes=0