Hang on RIL_MQTT_QMTPUB in Ql_Mqtt_Recv_Register's Function (RIL Task)

Hi
I’m working on a M66 device that connects to a thingsboard server and apart from publishing sensor values to server (over MQTT), it subscribes to a RPC Topic.

As you know RPC Commands gets published at a topic with a specific ID at end; device gets it and after processing, have to publish result in another topic (if need).
Publishing data over MQTT worked with no problem, so I register a MQTT receive callback function at the main task to achieve RPC Commands (I test registering in another task, no difference):

// Register MQTT recv callback
Ql_Mqtt_Recv_Register(MqttReceiveHandler);

then in MqttReceiveHandler, I call another function named ProccesMqttRPC and at the end of it, I call RIL_MQTT_QMTPUB as like below, but it cause to hang:

ret = RIL_MQTT_QMTPUB(ConnectID_0, 0,
                      QOS0_AT_MOST_ONECE, 0, Topic,
                      Ql_strlen(JsonTempBegin2), JsonTempBegin2);

I Trace it, Hang cause when Ql_RIL_SendATCmd called in ril_mqtt.c…

I was very confused but tracing tasks realize me that publishing sensor values executes from the main task but publishing RPC Results executes from the Task 2 (proc_reserved1 = RIL)! As I mentioned, I test registering in another task, no difference to executing task…

so is it mean that we can’t publish from RIL tasks? what to do then if we want to publish when some data arrives?