How to fill Buffer with chebyMsg in NRT?

I wrote a synth that uses Shaper under the hood. I want to render a pattern with it using NRT.
Also I know, that I should initiate buffer in NRT server a bit different, but didn’t find any example how to use it with Buffer methods like .chebyMsg

(
var server = Server(\nrt2,
    options: ServerOptions.new
    .numOutputBusChannels_(2)
);

var buf = Buffer.new(server, 1024, 1);

var def = SynthDef(\drone1, {
	| shaperBuf |
	var numsynths = 8;
	var freq = \freq.kr(110);
	var freqs = numsynths.collect({
		freq + Rand(0.5, 2.5);
	});

	var random_amps_modulators = numsynths.collect({
		SinOsc.kr(Rand(0.25, 5), Rand(0, 160).mod(2pi)).range(0.01, 1);
	});
	var signals = (LFTri.ar(freqs) * random_amps_modulators).collect({
		| signal |
		Shaper.ar(shaperBuf, signal, 0.5)
	});
	var sig = signals * \amp.kr(-6.dbamp);
	var env = Env([0, 1, 0], [0.5, 9]).kr(2);
	sig = RLPF.ar(sig, freq * 5, 0.2);
	
	Out.ar(\out.kr(0), Splay.ar(sig * env));
});

def.add;

x = Pbind(
	\instrument, \drone1,
	\dur, 8,
	\octave, 4,
	\note, Pseq([\A, \Cm, \A, \CM7].chordProg, inf),
	\amp, -10.dbamp,
	\shaperBuf, buf
).asScore(duration: 32, timeOffset: 0.001);

// Here I try to fill this buffer
x.add([0.0, buf.cheby([1, 0.5, 1, 1, 0.25, 2]).allocMsg]);

x.add([0.0, [\d_recv, def.asBytes]]);
x.sort;

x.recordNRT(
    outputFilePath: "~/drone.aiff".standardizePath,
    sampleRate: 48000,
    headerFormat: "AIFF",
    sampleFormat: "int16",
    options: server.options,
    duration: 32
);

server.remove;
)

But result file is empty.
So how can I use chebyMsg with NRT?

So how can I use chebyMsg with NRT?

In your example, you actually don’t use chebyMsg.

Replace

x.add([0.0, buf.cheby([1, 0.5, 1, 1, 0.25, 2]).allocMsg]);

with

x.add([0.0, buf.allocMsg]);
x.add([0.0, buf.chebyMsg([1, 0.5, 1, 1, 0.25, 2])]);

and it should work.