connect_async error only on Windows

[virtuosonic]

I have the following mosqpp::mosquittopp class constructor that when reaches the connect_async call returns 8 (MOSQ_ERR_TLS) when running in Windows 11 or 10 but on Ubuntu 24 LTS it works fine.

MqttClient::MqttClient() :
	mosquittopp("myid")
{
	const char* cafile = "ca.crt";
	if(!filesystem::exists(cafile))
		throw runtime_error("ca.crt not found");
	tls_set(cafile);
	tls_opts_set(0);
	const char* mq_user ="machine";
	const char* mq_pwd = "password";
	username_pw_set(mq_user,mq_pwd);
	const char* host = "myserver.com";
	int port = 8883;
	int keepalive = 60;
	auto res = connect_async(host,port,keepalive);
	if(res) qDebug() << "connect_async returned " << res << " " << mosqpp::strerror(res);
	subscribe(nullptr,"+/info/hw");
}

but if I replace connect_async() with connect() it works

I have used mosquitto 2.0.18 on both OS and also 2.0.20 on Windows with the same behavior.

loop_start() is called inside main() after instantiating the class